Level 1 gateway controlling broadband communications for video dial tone networks

ABSTRACT

In advanced digital networks for providing selective point-to-point communications between subscribers terminals and broadband server equipment operated by a plurality of independent information service providers, routing through the network is controlled by functionality identified as a Level 1 Gateway. In an enhanced video dial tone network additionally providing an array of broadcast services from multiple providers, the Level 1 Gateway also provides high level control over at least some of the broadcast services. The Level 1 Gateway will perform a variety of functions including communications port management of transmissions of information between subscribers and servers, processing of billing information and session management. The Level 1 Gateway generates menus of providers and broadcast services, either as a function of providers and services available through a particular portion of the network or in a customized fashion specified by individual subscribers. The Level 1 Gateway may also provide a PIN number functionality, e.g. to permit parents to limit which providers and broadcast services that their children can access. The Level 1 Gateway is itself an interactive device in that subscribers can input information and receive display information from the Gateway to define or modify their own video dial tone service through the network.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of pending U.S. patentapplication Ser. No. 08/304,174 filed Sep. 12, 1994, the disclosure ofwhich is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to routing and access control and billingfunctionalities in video distribution networks capable of providingsubscribers with access to multiple information service providers.

ACRONYMS

The written description and drawings use a large number of acronyms torefer to various services and system components. Although generallyknown, use of several of these acronyms is not strictly standardized inthe art. For purposes of this discussion, acronyms therefore will bedefined as follows:

Asymmetrical Digital Subscriber Line (ADSL)

Asynchronous Transfer Mode (ATM)

ATM Adaptation Layer (AAL)

ATM cell Adaptation Unit (AAU)

ATM Packet Demultiplexer (APD)

Broadcast (BC)

Broadcast Consolidation Section (BCS)

Broadcast Service Area (BSA)

Carrier Access Billing System (CABS)

Cell Loss Priority (CLP) bit

Central Office (CO)

Customer Record Information System (CRIS)

Customer Premises Equipment (CPE)

Digital Cross-connect Switch (DCS)

Digital Entertainment Terminal (DET)

Drop and Continue (D/C)

Electrical to Optical (E/O)

Ethernet (ENET)

First-In-First-Out (FIFO) buffers

Header Error Check (HEC) word

Integrated Services Digital Network (ISDN)

Interactive Multimedia Television (IMTV)

Level 1 (L1)

Level 1 Gateway (L1GW)

Level 2 (L2)

Level 2 Gateway (L2GW)

Local Loop Distribution (LLD) network

Local Video Access Node (LVAN)

Media Access Control (MAC)

Moving Pictures Experts Group (MPEG)

Network Interface Controller (NIM)

Network Interface Device (NID)

Operations and Support System (OSS)

Optical to Electrical (O/E)

Over-the-Air (OTA)

Packetized Elementary Streams (PES)

Payload Type (PT)

Pay-Per-View (PPV)

Permanent Virtual Circuit (PVC)

Permanent Virtual Circuit Controller (PVCC)

Personal Identification Number (PIN)

Physical Layer Convergence Protocol (PLCP)

Plain Old Telephone Service (POTS)

Program Identification (PID) number

Program Reference Clock (PRC)

Public Access Channel (PAC)

Public Switched Network (PSN)

Quadrature Amplitude Modulation (QAM)

Quadrature Phase-Shift Keyed (QPSK) modulation

Time-Division Multiple Access (TDMA)

Vestigial Sideband (VSB) modulation

Video Dial Tone (VDT)

Video Information Provider (VIP)

Video Information User (VIU)

Video Network Hub (VNH)

Video Provider Service Center (VPSC)

BACKGROUND ART

Distribution of full motion video data has evolved from early televisionbroadcasting to meet viewer demand. Earliest video distribution was bypoint-to-point wiring between a camera and a video monitor. This wasfollowed by scheduled television broadcasting of programming over thepublic air waves. In the 1960s, Community Antenna Television (CATV) waschartered to provide off-air television signals to viewers in broadcastreception fringe areas. Later, under FCC regulation, the CATV industrywas required to provide local access and original programming inaddition to off-air broadcast signal distribution.

In response, several sources of cable network programming wereestablished. Because of the wide bandwidth available on cable televisionsystems, additional channels were available for the new programming.However, programming was generally prescheduled, with the viewer left totune to the designated channel at the appointed time to view aparticular program.

To increase revenues, cable television systems have initiateddistribution of premium channels viewable only by subscribers havingappropriate descramblers. The subscriber tunes the descrambler toreceive a premium channel, descramble the video and audio informationand supply a signal capable of reception on a standard television set.Pay-per-view programs, which evolved later, include recently releasedmovies, live concerts and popular sporting events. Subscribers wishingto view a pay-per-view program place an order with the cable operator.At the designated time, the subscriber's descrambler is activated bysome control from the cable operator to permit viewing of thepay-per-view programming. However, the subscriber is still restricted toviewing the programming at the scheduled time. There is no capability ofdelivering programming to a subscriber on demand, that is, immediatelyor at a subscriber-specified time and date.

More recently, several different wideband digital distribution networkshave been proposed for offering subscribers an array of video services,including true Video On Demand service. The following U.S. Patentsdisclose representative examples of such digital video distributionsnetworks: U.S. Pat. No. 5,253,275 to Yurt et al., U.S. Pat. No.5,132,992 to Yurt et al., U.S. Pat. No. 5,133,079 to Ballantyne et al.,U.S. Pat. No. 5,130,792 to Tindell et al., U.S. Pat. No. 5,057,932 toLang, U.S. Pat. No. 4,963,995 to Lang, U.S. Pat. No. 4,949,187 to Cohen,U.S. Pat. No. 5,027,400 to Baji et al., and U.S. Pat. No. 4,506,387 toWalter. In particular, Litteral et al. U.S. Pat. No. 5,247,347 disclosesa digital video distribution network providing subscribers with accessto multiple Video On Demand service providers through the publicswitched telephone network, as described in more detail below.

U.S. Pat. No. 5,247,347 to Litteral et al., the disclosure of which ishereby incorporated in its entirety into this disclosure by reference,discloses an enhanced public switched telephone network which alsoprovides a video on demand service to subscribers over the publicswitched telephone network. A menu of video programming information isdisplayed at the subscriber's premises by a set-top terminal and a TVset. The subscriber may transmit ordering information via the publicswitched telephone network to the independent video informationproviders. Video programming may be accessed and transmitted to thesubscriber directly from a video information provider (VIP) or through avideo buffer located at a central office (CO) serving the subscriber.

Connectivity between the central office and the subscriber fortransmission of video data is provided by an asymmetrical digitalsubscriber line (ADSL) system. ADSL interface units at the centraloffice multiplex digital video information with voice information to betransmitted to the subscriber and support two-way transmission betweenthe subscriber's line and the X.25 packet data network of one or morecontrol channels. A complimentary ADSL interface unit at thesubscriber's premises separates downstream video control signals andvoice telephone signals from the line and multiplexes upstream controlsignals and voice telephone signals onto the line.

A subscriber can request transmission of video data using a telephoneinstrument by dialing a Voice Response Unit (VRU) of a video gatewaydevice, through the voice telephone switch and dialing in selectioninformation. Alternatively, the user can access the video gateway deviceand select a video using a remote control device, the set-top terminaland the control signaling channel through the network. The VIP'sequipment identifies the requested title and determines if the title isavailable.

If the title is found, the corresponding data file is opened and areserve idle communications port is identified for transmission of thevideo data to an input node of a digital cross-connect switch (DCS). Thevideo data file is transmitted from the VIP's video storage device,through the DCS, to the designated ADSL interfaces for transmission tothe requesting subscriber's premises. The ADSL interface on thesubscriber premises demultiplexes the broadband program transmission offof the subscriber loop and applies the digital data stream to a decoderunit in the set-top terminal. The decoder unit decompresses the audioand video data, and converts the digital audio and video tocorresponding analog signals. The decoder can supply baseband analogaudio and video signals to a television receiver, or these analogsignals can be modulated to a standard television channel frequency foruse by the television receiver.

The prior art video networks have not addressed many problems whicharise when the networks must be adapted to provide end users with equalaccess to multiple video information providers. For example, the priorart documents do not suggest an efficient procedure for accumulatingusage data and billing for the switched network broadband connectivityto multiple providers. Also, the prior art systems have not addressedthe need for the interactions of the end users with the video dial tonenetwork to be readily adaptable to end user demands as well as the needto provide equal access to all of the broadcast and interactive serviceproviders available to each end user. Thus a need clearly exists for anenhanced network control and billing system, which is both efficient andhighly user friendly.

DISCLOSURE OF THE INVENTION

The principle object of the present invention is to provide a seamless,smooth approach for connecting a video information user (VIU) to thevideo information provider (VIP) of their choice, in a multiple providerenvironment. The connection to the VIP of choice must be provided in anon-discriminatory manner that makes it easy for the user to get to thatparticular provider.

One more specific objective of the present invention is to provideeffective techniques for billing for the communication connectivityservices between multiple information service providers and end usersthrough a broadband network.

Another objective of the present invention is to provide efficienttechniques for informing subscribers of information service providersavailable to them through the network and responding to subscriberselections of providers to establish communication between subscribersand providers. This objective might include development of enhancedtechniques for offering subscriber menus of available VIP's and or aVIP's.

A further objective of the present invention is to develop enhancedmechanisms to allow an end user to interact with a selectiveconnectivity broadband communication network to customize servicesprovided to that subscriber through the network.

Another objective of the invention is to provide enhanced control overestablishment of communications between a subscriber and a particularinformation service provider, e.g. so that only authorized subscribersof that provider can communicate and/or so that subscribers canpersonally limit who can use their network service to access aparticular provider.

Another objective is to develop network control means, providing one ormore of the required enhanced functionalities discussed above, which isreadily adaptable to use in a variety of different types of videodistribution networks.

The present invention provides a number of the detailed network featuresneeded to offer a truly effective video dial tone service. Inparticular, the present invention provides a number of enhanced networkfunctionalities through a gateway node, referred to as the `Level 1Gateway`. In a network providing access to multiple service providers,the user identifies the provider of choice to the Level 1 Gateway. Inresponse, the Level 1 Gateway controls the broadband routingfunctionality of the network to establish a downstream broadbandcommunication link and a two-way communication signaling link betweenthe provider and the user.

The Level 1 Gateway accumulates usage data for billing purposes. Forexample, in one embodiment a billing system processes the usage data tobill the service provider for connect time for the broadbandcommunication links. The VIP's then bill their individual subscribers.Alternatively, the billing system can process the broadband usageinformation together with rate information from the service providers toproduce combined bills for direct billing to the subscribers.

The Level 1 Gateway receives notification of the status of broadbandcommunications links as they are being set up and during ongoingcommunications through those links. The Level 1 Gateway therefore caninform a subscriber when a requested session can not be set up with aselected service provider, i.e. because the provider's server ports areall busy or because the subscriber is not registered with the particularprovider or due to some technical problem. The Level 1 Gateway alsorecognizes when an established link develops a fault or is interruptedand can stop accumulating usage or billing data regarding that link. TheGateway can also notify the subscriber and/or the service provider ofthe failure.

The Level 1 Gateway will also store various information relating to eachsubscriber's services and control service through the networkaccordingly. At least some of this stored data is accessible to thesubscriber through a direct interaction with the Level 1 Gateway. Forexample, the user can identify certain service providers to the Level 1Gateway and define an authorization code or identification number whichmust be input before the network should provide a session with equipmentoperated by those providers.

Many of the functions of the Level 1 Gateway relate principally to setup, monitoring and billing for point-to-point type interactive sessions.However, a number of the Gateway functions also apply to broadcastservices. For example, the interaction with the Level 1 Gateway can beused to advance order upcoming broadcast pay-per-view events. At thetime for the event to begin, the Level 1 Gateway will transmitappropriate notice to the ordering subscriber's terminal. In response,the terminal may display the notice to the subscriber or the terminalmay automatically turn on and/or tune to the appropriate communicationlink through the broadcast network to obtain the ordered event. Theinteractive features of the Level 1 Gateway also permit subscribers tospecify limitations they wish to place on their broadcast services, e.g.total number of hours of usage within some defined interval and/or timeof day/week of permitted usage. The Level 1 Gateway will then controlthe broadcast network and/or the subscriber's terminal in accord withthe limits defined by the subscriber.

Examples of two different networks using the inventive Gatewayfunctionality are described in detail. As illustrated by such examples,the functions of this Gateway can be incorporated into a wide variety ofadvanced broadband communication networks.

The preferred network provides an enhanced video dial tone capability,allowing users to select service providers for an array of broadcastservices, as well as for point-to-point interactive services. Thepreferred network architecture comprises a backbone subnetwork and anaccess subnetwork. The backbone subnetwork provides point-to-pointtwo-way communication sessions for broadband interactive multimediacommunications signals with a selected one of the information providers.The access subnetwork receives digital broadband information signalsfrom the selected information provider, via the backbone subnetwork, fortransmission to one of the digital entertainment terminals. The accesssubnetwork also supplies control signals from the one digitalentertainment terminal to the backbone subnetwork for transmission tothe selected information provider. The access subnetwork also providesbroadcast transport. Specifically, the access subnetwork receivesbroadcast digital broadband information signals for selectivedistribution to the digital entertainment terminals. In the preferrednetwork architecture, the level 1 gateway of the present inventioninteracts with the respective subnetwork controllers to activate variousbroadcast services through the network and to set-up and tear downtwo-way communication sessions.

In the preferred implementation of this enhanced video dial tonenetwork, the backbone subnetwork comprises one or more asynchronoustransfer mode (ATM) switches. A permanent virtual circuit (PVC)controller serves as the ATM backbone subnetwork controller. The accesssubnetwork utilizes RF broadcast transport of both digital and analoginformation signals. The preferred implementation of the accesssubnetwork comprises hubs which convert ATM streams into digital packetstreams for RF broadcast and a number of local video access nodesconnected to each hub. The local video access nodes convert ATM streamsfor interactive services, as received from the ATM switch, into digitalpacket streams for RF transmission together with the RF broadcastsignals from the hub.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of an example of a first Video Dial Tonenetwork utilizing a Level 1 Gateway, in accord with the presentinvention.

FIG. 2 illustrates, in simplified form, the flow of messages betweenvarious components of the network of FIG. 1 during establishment of aninteractive broadband communication session.

FIGS. 2A to 2M illustrate various displays generated in response toinstructions from the Level 1 Gateway during broadband call processing.

FIG. 3 is a simplified block diagram of a communication network usingthe Level 1 Gateway of the present invention to control a wide range ofbroadcast and interactive multi-media services.

FIG. 4 presents a high-level overview of the control functions of anetwork of the type shown in FIG. 3 and delineates those functionsperformed by the Level 1 Gateway from those performed by other networkcomponents.

FIG. 5 is a block diagram of a distributed network architecture for thepreferred implementation of the broadband data full service type videodial tone network utilizing the inventive Level 1 Gateway according tothe present invention.

FIG. 6 is a block diagram of one of the video network hub offices shownin FIG. 5.

FIG. 7 is a block diagram of one of the local video access node type endoffices shown in FIG. 5.

FIG. 8 is a block diagram of one local loop distribution system portionof the network shown in FIG. 5.

FIG. 9 is a block diagram of the ATM backbone network and the controlsystems for the network shown in FIG. 5.

FIG. 10 illustrates, in simplified form, the flow of messages betweenvarious components of the network of FIGS. 5-9 during provisioning ofbroadcast channels.

FIG. 11 illustrates, in simplified form, the flow of messages betweenvarious components of the network of FIGS. 5-9 during activation ofbroadcast services to a new video information user.

FIG. 12 illustrates, in simplified form, the flow of messages betweenvarious components of the network of FIGS. 5-9 during set-up of anupcoming pay-per-view event.

FIG. 13 illustrates, in simplified form, the flow of messages betweenvarious components of the network of FIGS. 5-9 during activation ofpay-per-view event reception for a video information user who haspurchased the event.

FIGS. 14A and 14B illustrate, in simplified form, the flow of messagesbetween various components of the network of FIGS. 5-9 duringestablishment of an interactive broadband communication session with anIMTV VIP.

BEST MODE FOR CARRYING OUT THE INVENTION

The Level 1 Gateway of the present invention is useable in a variety ofdifferent broadband distribution networks which offer subscriber'sselective communication with a plurality of broadband or videoinformation service providers. FIG. 1 depicts one such network, referredto as a Video Dial Tone Network, which is a direct improvement over thenetwork disclosed in the above cited Litteral et al. Patent. For ease ofunderstanding, an overview of the Video Dial Tone network is set forthbelow, followed by a more detailed description of the functions of theLevel 1 Gateway in that network. Subsequent sections provide an overviewof the preferred network architecture, a detailed description of thepreferred network architecture and a discussion of the Level 1 Gatewayoperations in the context of the preferred network architecture.

Architecture of Basic Video Dial Tone Network

FIG. 1 is a block diagram an exemplary broadband network for providinginteractive services, such as video on demand, home shopping orpurchasing, home banking, medical information, ticket ordering, gaming,etc. In the network shown, the customer premises equipment (CPE)consists of a set top terminal identified as "DET" (digitalentertainment terminal) 100 and a telephone (POTS or ISDN). Theconnections to the central office utilize Asymmetrical DigitalSubscriber Line (ADSL) technology, typically over twisted wire pair,similar to that disclosed in the above cited Litteral et al. Patent. TheADSL connection provides a 1.5 Mbits/s downstream video informationchannel, a two-way telephone connection and a two-way 16 kbits/s controlchannel. The illustrated Video Dial Tone network architecture may usesome form of fiber extension in the actual subscriber loops, to provideservices to subscribers located more than 1.5 kilo-feet from a centraloffice (see e.g. U.S. Pat. No. 5,534,912, in the name of BruceKostreski, entitled "Extended Range Video On Demand System"). In thenetwork illustrated in FIG. 1, the drop to the subscriber's premises isalways a wired ADSL loop.

As shown in FIG. 1, the network interface module in the DET 100 connectsto an ADSL multiplexer/demultiplexer 201 similar to the in-home ADSLunit in the above discussed Litteral et al. Patent. The connectionbetween the network interface module of the DET 100 and the in-home ADSLunit 201 may consist of an RJ48C line and connectors. Such a linkcomprises six wire pairs, two for the broadband data, two for upstreamsignaling and two for downstream signaling.

Each ADSL subscriber line 203 will connect to an ADSL bay 205 located inor associated with the subscriber's local central office. For eachsubscriber line 203, the ADSL bay 205 includes an ADSLmultiplexer/demultiplexer similar to the central office ADSL unit in theabove discussed Litteral et al. Patent. The ADSL bay 205 providestransport for voice signals on the subscriber loop to and from theassociated voice switch 207. The ADSL bay 205 also connects to an accessconcentrator 209 for providing two-way signaling connections through anX.25 type packet switched data network 211. The ADSL bay 205 alsoreceives broadband digital signals for downstream transport over theADSL line 203 to each subscriber's premises from a digital cross connectswitch 213, labelled "Access DCS" in the drawing. One ADSL line 203 tothe home carries one channel of video programming and provides a singleoutput channel. The output channel can provide a video signal to a VCR(not shown) or to the TV set 100'. The various Access DCS switchesthroughout the network are controlled by switch controller 212.

If the ADSL bay 205 is local, i.e. located in the same telephone companycentral office as the cross connect switch DCS 213, the ADSL bay 205connects to the Access DCS 213 via an appropriate number of local DS1connections 215. In service areas where an ADSL bay does not carryenough traffic to warrant an associated Access DCS, the ADSL bay will belocated in a remote central office facility. Such a remote ADSL bayconnects to the Access DCS 213 via a SONET type optical fiber link 217providing an appropriate number of multiplexed channels to service thenumber of subscribers connected to the particular ADSL bay.

Video Information service Providers (VIP's) may access the downstreambroadband portion of the system at a hub location (not shown) within agiven LATA. The hub will not perform any switching. High capacityoptical fiber links are aggregated at the hub to provide each VIP with anumber of connections (e.g. one or more OC-3 links) from theirrespective video server to each Access DCS within the LATA.

The Access DCS 213 provides both point-to-point connections andpoint-to-multipoint connections. Individualized interactive services,such as Video On Demand, home shopping/purchasing and banking, usepoint-to-point connections wherein the Access DCS connects one broadbandinput port from a VIP's server to one output port going to thesubscriber's ADSL line. Narrowcast and broadcast services utilizepoint-to-multi-point connections of one input port to a plurality ofoutput ports.

The illustrated architecture of the Video Dial Tone network utilizes twolevels of gateways, both of which will communicate with subscribers'DET's via the X.25 data network 211 and the signaling channel on theADSL subscriber loops 203.

The Level 1 Gateway 221 performs a variety of network connectivityrelated functions, including communications port management oftransmissions of information between subscribers and servers, processingof billing information and session management. Normally, each subscriberaccesses the Level 1 Gateway (e.g. to select and access a particularVIP's server) by operation of a remote control device which causes thesubscriber's DET 100 to transmit data signals to the Level 1 Gateway viathe 16 kbits/s control channel and the X.25 packet switched data network211. The Level 1 Gateway transmits one or more selection menus to thesubscriber's DET 100 as screens of text data carried by the same pathback through the network.

In the present implementation, text or graphics information from theLevel 1 Gateway is displayed as a page of data. Alternatively, the textor graphics data could be overlaid on a video display received throughthe broadband network, e.g. over one of the broadcast channels carriedthrough the more advanced networks discussed below.

In a typical scenario, the user would turn on the DET terminal 100, andin response to data signals from the Level 1 Gateway 221, the terminalwould display an initial selection menu. The subscriber would input aselection, and in response to an appropriate data signal from the DET100, the Level 1 Gateway 221 would instruct the various networkcomponents to set up a virtual circuit to the level 2 gateway of aselected VIP for signaling purposes and a direct downstream path fromthe VIP's server through the digital cross-connect switch 213 for videotransmission.

The Level 1 Gateway 221 accumulates usage statistics relating to thebroadband communication links through the network and supplies thosestatistics to a billing system, e.g. to a carrier access billing system(CABS) 227 as shown in FIG. 1. The Level 1 Gateway 221 also exchangesvarious network operational status information with the switchcontroller 212 and with a video provider service center (VPSC) 231.

These and additional functions of the Level 1 Gateway are discussed inmore detail below.

A level 2 gateway provides a number of services for the InformationProviders. These services include transmission of menus of availableinformation to subscribers, searches of available information, targetedadvertisement insertion, previews, trailers, etc. The level 2 gatewaywill download video or audio menus to each subscriber's DET for display,thereby allowing each subscriber to select desired information. Once asubscriber makes a selection, the level 2 gateway will signal theappropriate server to schedule transmission of the selected informationthrough the established downstream video transmission path. The Level 1Gateway accumulates connectivity charge information for purposes ofbilling each called VIP. The level 2 gateway records transactions, e.g.movies viewed, by each subscriber for billing purposes. The level 2gateway also interacts with the DET 100 and controls the associatedservers to download executable program code for storage in the DETsystem memory.

The switch controller 212 monitors operations of the digital crossconnect switches 213 and provides appropriate information to the Level 1Gateway. For example, if the switch controller 212 indicates that abroadband communication link through one of the switches has failed forsome reason, the Level 1 Gateway will terminate its accumulation ofusage data for billing for the particular broadband session. The videoprovider service center (VPSC) 231 performs a related monitoringfunction with regard to the ADSL loops.

The ADSL bays 205 monitor communications over the subscriber lines 203by periodically enquiring as to the status of each on-premise ADSL unit201. The ADSL bays 205 in turn inform the video provider service center(VPSC) 231 of any detected failures via data connections to that center(only one such data connection is illustrated in FIG. 1). In thepresently preferred embodiment of the network of FIG. 1, the servicecenter (VPSC) 231 is manned operations support personnel. In response toa failure alarm indicating one of the ADSL lines is down, the center 231provides a display for review by one of the technicians. A VIP may alsocall in and indicate that the VIP's system 252 has detected some form offailure. Based on the displayed information and/or the information fromthe VIP, the technician decides whether in fact a failure has occurred.If so, the technician initiates an X.25 data call and transmission of amessage from the video provider service center (VPSC) 231 to the Level 1Gateway 221 identifying the failed link and instructing the Gateway 221to tear down the particular broadband link. The Level 1 Gateway 221terminates its accumulation of usage time data for that link andinstructs the switch controller 212 to tear down the link.

Upon detection of a fault and reporting thereof to the video providerservice center (VPSC) 231, personnel at the center can initiate actionto correct the fault. For example, if the switch controller 212 reportsa fault in a particular switch 213, the personnel at the service center(VPSC) 231 can call a technician at the central office housing thatswitch and have that technician test the switch and correct any faultsactually discovered. Similarly, if an ADSL bay 205 reports some fault onthe twisted wire pair 203 or loss of communications with the on-premisesADSL unit 201, the personnel at the service center (VPSC) 231 candispatch a repair technician to locate and correct the fault on the lineor in the on-premises unit.

As discussed in more detail with regard to later network embodiments, itis preferred for more advanced versions of the network that the functionof the video provider service center (VPSC) 231 be fully automated toinstruct the Level 1 Gateway 221 to stop billing data accumulation andtear down faulty broadband links without human intervention.

The Video Dial Tone network of FIG. 1 provides video on demand and otherbroadband interactive multimedia services offered by a plurality ofservice providers. For example, using the upstream data channel, thesubscriber can send a request for a particular movie from his VIP ofchoice, and the VIP's server will retrieve and transmit that movie as anMoving Pictures Experts Group (MPEG) digital data stream on the 1.5Mbits/s downstream channel to the digital audio/video processor in thesubscriber's DET 100.

Although other digital compression encoding schemes may be used, such asDIGICIPHER™, the preferred embodiments of the present invention utilizeMPEG encoding and decoding. MPEG (moving picture experts group) is abroad generic standard for video program compression, and MPEG 2 is asecond generation compression standard for packetized transport of oneor more compressed video program signals in a single stream. A number ofspecific compression algorithms will satisfy MPEG requirements.Typically, MPEG permits encoding of audio/video program materials intodigitized, compressed format at rates in the range of 1.5 to 6Mbits/sec.

In the illustrated network, the DET 100 includes a CPU, comprising a 386or 486 microprocessor and associated memory (RAM, ROM and EPROM) and anaudio/video decoder, controlled by the CPU. The audio/video decoderdecompresses the digitized broadband information. The preferredembodiment of the audio/video decoder comprises an MPEG video decoder,an MPEG audio decoder, and an MPEG demultiplexer for selectively routingMPEG encoded video and audio packets carried on the digital broadbandchannel to the MPEG video decoder and the MPEG audio decoder,respectively. The DET also includes a graphics display generator forgenerating displays of received text data, such as the initial turn-onselection menu, discussed in more detail below. The DET also includesdigital to analog converters and appropriate drivers to produce outputsignals compatible with a conventional television set from the decodedaudio/video information and the graphics display. Each DET also includesmeans to receive selection signals from a user and transmit appropriatedata signals over a narrowband channel through the particular videonetwork.

The digital entertainment terminal (DET) 100 is a programmable device towhich different individual video information providers (VIP's) candownload different applications software. At least one VIP, typically avendor of the DET, also can download portions of the operating system.The DET will permanently store only an operating system and a loaderprogram, to control initial communications with a Level 1 Gateway or tofacilitate initialization into a simplified CATV type mode of operation.

The structure and operation of the DET 100, outlined above, aredescribed in more detail in commonly assigned application Ser. No.08/250,791, filed May 27, 1994, entitled "Dynamically ProgrammableDigital Entertainment Terminal" (attorney docket no. 680-083), thedisclosure of which is entirely incorporated herein by reference.

Level 1 Gateway Functionality in Basic Network

Physically, the Level 1 Gateway is a mini-computer, and in the VideoDial Tone network of FIG. 1, that computer would have interfaces forX.25 packet data communications. In one implementation, the Level 1Gateway is a UNIX based machine, such as a Tandem Integrity typecomputer. Essentially, the Level 1 Gateway comprises a processor CPU,with associated RAM and ROM, as well as mass data storage and retrievalmeans, e.g. various disc drives. There is one Level 1 Gateway per LATA,as shown in FIG. 1. However, for service areas encompassing a number ofLATA's, the video dial tone network would include a plurality of Level 1Gateways.

FIG. 2 provides a somewhat simplified illustration of the process flow,with particular emphasis on the exchange of signals involved in settingup, carrying on and tearing down an interactive broadband sessionbetween a DET and a selected VIP's equipment.

To access the system, the customer turns on the digital entertainmentterminal (DET) 100. As shown at step S1 in FIG. 2, the DET transmits an"offhook" message upstream to the Level 1 Gateway servicing that DET.Specifically, the DET type terminal transmits an X.25 message throughthe upstream signal path to the access concentrator 209. This is ageneric off-hook message, and the message from the terminal 100 carriesno addressing. The access concentrator 209 identifies the off-hook DET100 by identifying the physical ADSL port on the access concentratorthrough which it received the message and assigns a signalling addressto that terminal. The access concentrator 209 populates the correctX.121 address for the sender into the call request message and populatesthe correct X.121 address for the Level 1 Gateway 221 into the message.The access concentrator 209 sends the addressed message through the X.25packet switched network 211 to the Level 1 Gateway 221. Thus, the callis terminated in the Level 1 Gateway 221 as an X.25 data call, and atwo-way virtual circuit is dedicated to data communications between theGateway 221 and the DET 100 for the duration of the call set-upprocessing. The X.121 addresses are used for call set. During callset-up an available X.25 virtual circuit is defined for data flow inboth directions, and subsequent packet transmissions will utilizeappropriate packet headers to follow that virtual circuit node-to-nodethrough the X.25 packet network.

The Level 1 Gateway 221 includes a file for each subscriber containingthe subscriber's billing telephone number, the subscriber's X.121address for signaling purposes, and the port identification of thebroadband connection of the subscriber's line to the digitalcross-connect switch (DCS) 213 serving the particular subscriber. Whenthe Level 1 Gateway 221 receives the addressed message from the accessconcentrator 209, that Gateway uses the X.121 address of the caller tocheck its internal database to determine if the caller is a valid videodial tone customer (S2). If the caller is not a valid customer, thesystem tears downs the session (S2₁). Although not shown as a separatestep in FIG. 2, the Level 1 Gateway will typically transmit aninstruction to the DET 100 to display some service denial message, suchas that shown in FIG. 2A, as part of the operations to terminalcommunications with the particular DET. If the caller is a validcustomer, the Level 1 Gateway 221 transmits an X.25 call accept messageback to the DET 100 (S2₂) and waits for the first application levelmessage.

Once the call is accepted and an X.25 signalling link is provided, theset-top terminal DET 100 sends an initiation message that says "hello"(S3). This "hello" message includes basic information such as a customerpremises equipment (CPE) identifier and a CPE type designation of theparticular DET. This information is primarily for the level 2 gateway.The Level 1 Gateway 221 normally transmits back menu information, asASCII data in X.25 message form (S4). The menu gives the customer theoption to ask for a particular video information provider (VIP), such asthe VIP operating the system 252. In the illustrated example, each VIPprovides a level 2 gateway and some form of broadband information server252 connected to the network.

Each level 2 gateway is assigned a 4-digit code. Some DET's will havethe option of preassigning a 4-digit VIP code, so that such a terminalalways automatically transmits the preassigned 4 digit VIP codeimmediately with the initial "hello" message. Inclusion of the 4 digitVIP code in the initial message indicates the subscriber's VIPpreference. As a result, the customer could always go to the samepreferred VIP, and the customer need never see a VIP selection menu. TheLevel 1 Gateway 221 checks the validity of the VIP code. Assuming theVIP code is valid, the Gateway 221 would see that this call is from avalid customer and initiate signaling communication with the particularVIP's level 2 gateway immediately.

If the Level 1 Gateway 221 detects that a received VIP preference codewas not a valid VIP identifier code, the Gateway 221 transmits a messageto the DET 100 through the signaling channel instructing the DET todisplay the notice shown in FIG. 2B. As shown in that drawing, thedisplayed notice informs the customer that the video provider preferencewas not recognized. The notice also informs the subscriber that a VIPselection menu will be forth coming. The Level 1 Gateway will wait forsome finite period to permit the subscriber to review the displayednotice and then proceed with call processing as if a standard "hello"message had been received (without any VIP preference code), asdiscussed in more detail below.

The DET and/or remote control associated therewith will have appropriatekeys to write a VIP preference into the memory of the DET 100. The DET100 and/or remote control will also have a key or keys for input of aninstruction to override the preprogrammed VIP preference. If thesubscriber overrides the preference, the DET 100 will issue a normal"hello" message without the VIP identifier code, and processing willadvance as if a standard "hello" message had been received (without anyVIP preference code), as discussed below.

If there is no VIP preference code in the X.25 "hello" message (see S3)or the preference code was invalid, the Level 1 Gateway 221 sends abanner followed a few seconds thereafter by a menu, through thedownstream signaling channel (34). The banner display (FIG. 2C) depictsan initial greeting, such as "Welcome to Bell Atlantic Video Dial ToneServices". The menu is a screen of text and/or graphic images listingVIP's available to this customer. FIG. 2D shows the format of the menudisplay. As shown, the menu displays the number of available providers(VIP's), lists each provider by two-digit code, and gives the name ofeach provider. Although shown as two separate displays, the banner andfirst menu page can be combined into one display page requiring only asingle transmission by the Level 1 Gateway. Alternatively the banner maybe eliminated. One line of the menu page can indicate that the menuincludes additional pages and what keys to actuate to request the nextpage from the Level 1 Gateway. If a customer selects an additional VIPmenu page, the DET 100 transmits an appropriate request message to theLevel 1 Gateway 221, and that Gateway transmits back another page ofdata for display.

The remote control or keypad input on the set-top terminal has arrowkeys which allow the user to select from the VIP's listed on thevisually displayed menu. The subscriber reviews the menu on theirtelevision set, and operates the arrow keys to move a cursor across themenu to an appropriate point on the screen, after which the user pressesan <ENTER> key on the keypad or remote control. Alternatively, the usercan enter the two digits shown in the VIP's listing beside the name andthen press <ENTER>. In response to either type of VIP selection input,the DET 100 transmits an appropriate data signal upstream through thenetwork to the Level 1 Gateway 221 (S4). When the Level 1 Gateway sendsthe selection menu to the set-top terminal, if no response is receivedfrom the DET 100 within a predetermined period, the Level 1 Gatewaytears down the X.25 signaling link to that terminal. As discussed inmore detail below, the Level 1 Gateway 221 will normally receive theselection input message from the DET 100 within the predetermined periodand will translate that message into the 4 digit code for the selectedVIP's level 2 gateway.

The VIP menu, formatted as pages of data in the manner shown in FIG. 2D,is created as a function of which VIP's have access to each accessdigital cross-connect switch (DCS). As shown in FIG. 1, the video dialtone network uses a number of DCS's serving different geographical areasand different subscribers. The DCS's will typically be in differentcentral offices. Not all VIP's connect to and provide services throughall of the DCS's. When a subscriber accesses the Level 1 Gateway 221,that Gateway knows which DCS services that subscriber and which VIP'shave server ports on that DCS. The Level 1 Gateway 221 therefore limitsthe VIP's listed on the menu sent to the subscriber's DET 100 to thoseVIP's providing services through the particular DCS. In the currentlypreferred embodiment, the information on the menu that pertains to thevarious available providers is kept alphabetically. Alternatively, theLevel 1 Gateway 221 may randomly rearrange the order of the VIP listingsin the menu on some periodic basis.

The present invention also permits the customer to modify the menu totheir own personal tastes. Thus, if there are ten providers availablethrough a particular DCS, and the customer has opted to see only threeon a regular basis, the Level 1 Gateway recognizes the customer's DETand transmits a customized menu listing only those three to thecustomer's DET terminal for display.

As outlined above, the user typically reviews the menu displayed on theTV screen and selects one of the available VIP's. In response, theuser's DET 100 transmits a signal identifying the number of theselection from the menu upstream to the Level 1 Gateway 221 (S5). TheLevel 1 Gateway always knows what menu it sent to the particular DET.The Level 1 Gateway 221 uses the precise menu information and a table ofVIP identifier codes to translate the selection input signal from theDET 100 into an actual 4-digit VIP identification address for the level2 gateway of the particular VIP that the person selected. The Level 1Gateway 221 sends an X.25 message to the DET 100 saying please waitwhile we connect to the VIP's system 252 (S6). In response, the DETproduces a standby display, such as the display shown in FIG. 2E. Thedisplay preferably will identify the VIP that the customer is awaitingconnection to. The row of `Q`s in FIG. 2E indicate the display space inwhich the VIP's name is inserted.

The Level 1 Gateway 221 next goes over a locked up "permanent" virtualcircuit through the X.25 network, to communicate with the level 2gateway of the VIP's system 252. Specifically, the Level 1 Gateway 221contacts the level 2 gateway and indicates, through a standard message,that it has a customer calling (S7). The Level 1 Gateway 221 identifiesthe customer to the level 2 gateway by sending the standard billingtelephone number for the calling customer to the level 2 gateway. TheCPE identification information and the CPE-type information for the DET100 that was sent in the initial origination message is also sent to thelevel 2 gateway (VIP) at this time. The VIP's level 2 gateway may acceptor reject the call (S8) after receiving the initial request indicating acustomer is available.

When the Level 1 Gateway 221 initially asks the level 2 gateway if acalling subscriber is a valid customer, the Level 1 Gateway expects aresponse accepting or rejecting the call within a set time, and if theresponse is not received in that time, the Level 1 Gateway sets off anappropriate alarm. The Level 1 Gateway 221 would inform the DET 100 ofthe inability to reach the selected VIP and instruct the DET to providean appropriate display through the TV 100' to the user. The displaymight inform the user that there is some form of network problem andeither instruct the user to try again later (FIG. 2F) or to selectanother provider (FIG. 2G), depending on whether other providers areavailable as indicated on the VIP selection menu presented to thissubscriber. Alternatively, the Gateway 221 could use one of theprovider--unavailable message of FIGS. 2H and 2I.

The level 2 gateway may reject the call for a number of reasons. Forexample, that gateway may look up the caller's telephone number in alist of the VIP's subscribers' telephone numbers to determine if thecaller in fact subscribes to the VIP's services. The level 2 gateway mayalso check on the calling subscriber's current billing/payment status.Non-subscribers and/or subscribers who are delinquent in paying theirbills to the VIP would be rejected. The level 2 gateway might alsoreject a call if all its existing server output ports on the DCS 213serving the particular subscriber are currently in use. If the level 2gateway decides to reject a call, that gateway sends a message back tothe Level 1 Gateway 221 indicating a rejection of the call (S8₁). Therejection message indicates the reason for the rejection. The Level 1Gateway 221 transmits a message to the DET 100 instructing that terminalto display an appropriate one of the notices shown in FIGS. 2H through2L as a call rejection notice on the associated TV 100' (S8₂).

The specific rejection notice displayed to the calling subscriberdepends on the circumstances of the particular call rejection. If theprovider can not service the broadband call at this time because of someserver failure, the message would indicate to the user that the provideris not available. If no other providers are available to the particularcaller, the message would suggest that the caller try again later, as inFIG. 2H. Alternatively, if the caller has access to other providers themessage would suggest that the caller select another provider, as shownin FIG. 21. If all of the selected the provider's server ports are busy,the Level 1 Gateway would instruct the DET 100 to display one of thebusy notices shown in FIGS. 2J and 2K, depending on whether or not otherproviders are available to the particular caller. If the VIP arbitrarilydenies access, e.g. because the caller is not a recognized subscriber orhas not paid her bill, then the Level 1 Gateway would instruct the DET100 to display a call denial message, such as shown in FIG. 2L.

Alternatively, the level 2 gateway accepts the call, provides a serveroutput port and gives an identification for that port to the Level 1Gateway 221 (S8₃). In response, the Level 1 Gateway 221 transmits theX.121 address of the calling customer to the level 2 gateway (S9). TheLevel 1 Gateway 221 looks in its internal record to find the broadbandport number for the requesting customer and sends a message to theswitch controller 212 instructing one of the DCS's 213 to connect theserver port the VIP provided to the broadband port for the subscriber,to thereby set up the broadband communication link (S12). The level 2gateway uses the customer's X.121 and its own X.121 address to initiatea new X.25 signaling communication type call to the subscriber's DET 100(S11).

If the broadband connection is successfully set up, the switchcontroller 212 transmits back an indication that the broadbandconnection has been established. Then the Level 1 Gateway 221 tears downits own X.25 signaling connection with the subscriber's DET 100. At thattime, the Level 1 Gateway 221 informs the level 2 gateway that it hasset up a good broadband link, and the Level 1 Gateway 221 initiates abilling record for the call. An interactive broadband session ensues viathe broadband and signaling links.

Alternatively, if the switch controller 212 could not establish thebroadband communication link, the controller 212 informs the Level 1Gateway 221 of that fact and the specific reason it could not establishthe broadband link. The Level 1 Gateway passes that information on tothe level 2 gateway. The codes identifying the basis for the failure tocomplete the broadband call provide the level 2 gateway information asto whether the failure is a one time condition or is continuous, whetheror not the failure is network-wide, etc. This information is useful tothe operator of the level 2 gateway, for example, to determine whetherto continue to send requests for broadband channels through the Level 1Gateway or to suspend operations until receiving notice that a networkfault has been cleared. The Level 1 Gateway 221 also provides anappropriate message through the signaling channel for display by the DET100 informing the customer. The displayed message might offer thecustomer the option to select another VIP if the fault relates only toaccessing the selected VIP (similar to FIG. 2I), and if the customerdoes so, the call processing begins again with transmission and displayof the VIP selection menu.

When a broadband session ends, e.g. as indicated by an exchange ofappropriate messages between the DET and the level 2 gateway (S13), thelevel 2 gateway instructs the Level 1 Gateway 221 to tear down thebroadband session connection (S14). The instruction includes thecustomer's billing telephone number and the server port identificationfor the VIP port used for the broadband communication. In response, theLevel 1 Gateway 221 stops the billing timing for that broadband sessionand transmits an instruction through the switch controller 212 to theDCS 213 to tear down the broadband connection between the server portand the customer's broadband port (S15).

The port identifications are always ten-digit numbers. Of the digits,the second, third and forth digit positions identify the digitalcross-connect switch (DCS) in question. At any point, when a VIP's level2 gateway sends a ten-digit server port identification number to theLevel 1 Gateway, for setting up or tearing down a link to a particularsubscriber port, the Level 1 Gateway compares the second, third andfourth digits to the corresponding digits of the subscriber's portidentification to determine if the server port is in fact on the samedigital cross-connect switch as the subscriber's port. If the digits donot match as they should, the Level 1 Gateway informs the level 2gateway of the error and requests a new server port identification.

The Level 1 Gateway 221 creates a log record that contains specificinformation including the time that the Level 1 Gateway received or senteach message. Information of a failure is furnished by the switchcontroller 212. The switch controller will indicate between which portsthe failure occurs. The Level 1 Gateway then notifies level 2 gatewayand possibly the set-top terminal that a network failure has occurredand the communication link is lost.

The Level 1 Gateway collects usage statistics for billing purposes. TheVIP's may choose to collect audience statistics through the level 2gateways. In the preferred implementation of the video dial tone networkof FIG. 1, the subscriber may be charged a flat monthly charge, e.g. onher telephone bill, for video dial tone service. The usage sensitivecharges for the broadband connections through the network, however, goto the VIP's. However, an alternate implementation of the presentinvention combines network usage charges with VIP's service charges intoa single bill to be sent directly to each subscriber.

For billing purposes, the Level 1 Gateway creates a billing record foreach call which resulted in an actual broadband connection through oneof the digital crossconnect switches (DCS's). The billing recordidentifies the level 2 gateway, by its 4-digit code. The billing recordincludes an identification of the customer by billing telephone number,the type of call (e.g. ADSL or fiber), an identifier of the digitalcross connect switch (DCS) which provided the broadband connection, anidentifier of the particular Level 1 Gateway that serviced the call, theconnect date, the time that the broadband connection was firstestablished, and the elapsed time until tear-down of the broadband link.The Level 1 Gateway supplies all of this information directly through atransmission link to the telephone company's carrier access billingsystem (CABS) 227 for processing into appropriate invoices for billingthe VIP, in a manner substantially similar to billing of anInterexchange Carrier. The usage data can be downloaded periodically tothe CABS 227, or the Level 1 Gateway may initiate downloading inresponse to a manual request from the system administrator. Each VIPestablishes its own rates and procedures for actually billing the endusers. The Level 1 Gateway and CABS systems may also accumulate data andbill the VIP's for the X.25 signaling links, but in the currentimplementation there would not be any separate charges for the variousX.25 signaling communications.

In the illustrated implementation, the video dial tone networkessentially bills the VIP for the broadband connection time, and eachVIP in turn bills its subscribers. As an alternative, the Level 1Gateway 212 can supply the broadband usage information to a customerrecord information system or `CRIS` (not shown). CRIS would storeinformation as to each VIP's service charges and would process thatinformation together with the usage data from the Level 1 Gateway togenerate a combined bill for the end user/subscriber. The subscriberwould pay the billed amount to the network operations company, typicallythe local telephone company, and the network operations company woulddivide the received revenues between itself and the VIP(s).

To change connections from one VIP to another, the user initiates asign-off procedure with the first VIP. The first VIP's level 2 gatewayinstructs the Level 1 Gateway 221 to tear down the broadband link, asdiscussed above, and the DET 100 initiates a new VIP selection procedurewith the Level 1 Gateway in a manner similar to the initial turn-oncommunication discussed above.

If the user simply turns off the set-top terminal DET 100 in the middleof a video session, the DET will send some form of "terminate" messagethrough the signaling link to the level 2 gateway. The level 2 gatewaywould instruct the Level 1 Gateway 221 to tear down the broadbandconnection and stop billing in the above discussed manner. When thesubscriber turns the DET 100 back on, that terminal begins a newcommunication with the Level 1 Gateway 221 in the normal manner. If forsome reason the broadband link with the first VIP has not yet been torndown, e.g. because of some failure or time delay incurred in that VIP'ssignaling the Level 1 Gateway 221 to take down the first connection, theLevel 1 Gateway will discover this fact at the time it instructs theswitch controller 212 to set up the second connection to the newlyselected VIP. At that time, the Level 1 Gateway 221 will instruct theswitch controller 212 to tear down the first connection and set up thesecond connection.

The Level 1 Gateway also offers a personal identification number (PIN)control functionality. This gives the end user the ability to assign aPIN number to one or more of the VIP's shown on the VIP selection menu.For example, certain VIP's might show materials which a parent mightdeem unsuitable for young children to view. Such a parent would assign aPIN to those VIP's. When someone selected such a VIP from the menu, theLevel 1 Gateway 221 would instruct the DET 100 to output a promptingtype display and/or audio message requesting input of the PIN. Theparent would know the PIN and be able input the correct PIN, using theDET remote control, to access the VIP. However, a child not knowing thePIN would not be able to give the correct response to the prompt, andthe Level 1 Gateway 221 would deny access.

In addition to the VIP selection options, the initial menu from theLevel 1 Gateway will offer callers the ability to interact with thatGateway to control their video dial tone service. With this feature, thesubscriber would initiate communications with the Level 1 Gateway inprecisely the same manner as for a call to a video information provider(VIP), as discussed above with regard to FIG. 2. In the menu format ofFIG. 2D, one or more of the VIP listing lines would identify Level 1Gateway interactions, e.g. for "Personal Options". Selection of one suchchoice from the menu initiates an interactive session between thesubscriber and the Level 1 Gateway. In the network of FIG. 1, thecommunications for this session will be entirely through the signalingchannel. The DET 100 transmits upstream signals through the signalinglink and the X.25 data call to the Level 1 Gateway 221, and the Gateway221 transmits text or graphics displays and instructions to the DET 100back downstream through that signaling path. In a further enhancedimplementation, the Level 1 Gateway would have broadband communicationcapabilities.

A "Personal Options" session with the Level 1 Gateway would step thesubscriber through a series of menus and inputs to select an option tomodify (e.g. PIN number or customize menu) and collect the informationfrom the subscriber needed to execute that option. For example, if thesubscriber selected the PIN number option, the Level 1 Gateway would askfor a four digit PIN number input from the subscriber and then ask whichVIP's on the menu the subscriber wanted that PIN applied to. Thecurrently preferred implementation offers only a single PIN for allVIP's a subscriber chooses to restrict access to. Alternatively, theLevel 1 Gateway could offer to apply different PIN numbers to differentVIP's. A similar procedure permits a subscriber to set up a short listof VIP's that subscriber prefers.

In the implementation of FIG. 1, the "Personal Options" through theLevel 1 Gateway 221 are limited to PIN number and menu customization. Inmore advanced networks offering additional services, such as broadcastvideo and pay-per-view, this Level 1 Gateway feature would allow thesubscriber to set up and modify a wider variety of service options. Forexample, the Level 1 Gateway might offer a subscriber an option tospecify or change a level of broadcast service. As another personaloption, the Level 1 Gateway might offer a subscriber an "Hours ofService" control. If the subscriber selects this option, the Gatewaywould ask for input of a number for use as a threshold value. For eachweek (or other specified time interval), the Level 1 Gateway wouldmonitor the number of hours of service provided to that subscriber'sDET(s) and would terminate service to that subscriber's DET(s) if usageexceeded the threshold number input by the subscriber. This service timelimitation might have an attendant PIN number based override to permitsome member of the household (typically a parent) to override the hoursof service limitation. The Level 1 Gateway could similarly offersubscribers the option to specify time of day/week limitations and thenwould deny service at other times unless a valid PIN number wasreceived.

As noted during the above discussion, the Level 1 Gateway may receive anindication from the switch controller 212 that it can not establish adesired broadband connection. The controller 212 monitors operations ofthe individual DCS switches 213 at all times and will also inform theLevel 1 Gateway upon detection of a fault or interruption in anestablished broadband connection. The Level 1 Gateway 221 transmitsnotice of an inability to establish a desired broadband session to therequesting DET, using notices such as shown in FIG. 2F and 2G dependingon whether or not other VIP's are available to the particular subscriberat the time of the call. If the Level 1 Gateway 221 receives notice of afault in an already established session, the Gateway 221 stopsaccumulating billing data for that session and transmits an X.25 messageregarding the failure to the VIP's level 2 gateway. The level 2 gatewaymay provide an appropriate notice to the subscriber through thesignaling link, if that portion of the session is still operative.Alternatively, the Level 1 Gateway may initiate a new X.25 call to thesubscriber's DET 100 to provide an appropriate display notice.

The VPSC 231 monitors the operations of ADSL communications capabilitieson each subscriber's line. If the VPSC 231 detects a fault in a linecurrently engaged in a broadband communication session, and thetechnician at the center 231 determines that the fault is real, then theVPSC 231 makes an X.25 call to the Level 1 Gateway 221 and sends anerror message identifying the line to the Level 1 Gateway 221. TheGateway 221 stops accumulating billing data for that session andtransmits a message to the switch controller 212 to tear down thesession. Once the switch controller 212 provides a positiveacknowledgement to the Level 1 Gateway 221 that the session has beentorn down, the Gateway 221 provides a confirmation message to the VPSC231. The Level 1 Gateway also transmits an X.25 message regarding thefailure to the VIP's level 2 gateway. The level 2 gateway may provide anappropriate notice to the subscriber through the signaling link, if thatportion of the session is still operative. However, in the preferredembodiment, the level 2 gateway terminates its X.25 call to the DET 100,and the Level 1 Gateway initiates a new X.25 call to the subscriber'sDET 100 to provide an appropriate display notice regarding the linefailure. If the problem was line related, a network problem type displaynotice, such as shown in FIG. 2F, could be used. If the fault reportsuggested some defect in the DET or broadband communications from theADSL unit 201 to the DET 100, the Level 1 Gateway 221 would specify adisplay notice relating to the DET itself, such as that shown in FIG.2M.

The Level 1 Gateway 221 can also initiate an audit of the status of asubscriber's line. The Level 1 Gateway issues an audit request for thesubscriber line to the switch controller 212. The switch controller 212determines the status of the subscriber's line and informs Level 1Gateway whether the line is in service but idle, in service and inprogress, or out of service and idle. Similarly, the Level 1 Gateway 221can initiate an audit of the status of a source line from a server. TheLevel 1 Gateway issues an audit request for the server line to theswitch controller 212. The switch controller 212 determines the statusof the source or server line and informs Level 1 Gateway. For example,if the server line is operative but not involved in a connection, thereported connection status of the server line is "in service but idle".

When the Level 1 Gateway 221 instructs the switch controller 212 toestablish a broadband connection, the Gateway 212 expects a responsefrom the controller 212 within a predetermined time interval. If thecontroller 212 does not respond within the predetermined time interval,the Level 1 Gateway 221 will send an ABORT message to the switchcontroller 212 to cancel the session establishment message. The Level 1Gateway 221 also informs the level 2 gateway of the failure to establisha connection and provides an appropriate notice of the failure to thesubscriber through the X.25 signaling call still existent with the DET100. The Gateway 221 will also record the failure in an alarm file.

When the Level 1 Gateway 221 instructs the switch controller 212 to teardown a broadband connection, the Gateway 212 expects a response from thecontroller 212 within a predetermined time interval. If the controller212 does not respond within the predetermined time interval, the Level 1Gateway 221 will send an ABORT message to the switch controller 212 tocancel the original session establishment message, and the Gateway 221will also record the failure in an alarm file.

Presently Preferred Network

The above discussion has concentrated on operation of the Level 1Gateway in the cross-connect switched type basic Video Dial Tone (VDT)network, however, that Gateway will work equally well in a variety ofother enhanced Video Dial Tone network architectures with a wider rangeof service capabilities. Adaptation of the Level 1 Gateway to othernetwork architectures principally requires that, instead of interactingwith a switch controller and digital cross-connect switches (DCS's), theLevel 1 Gateway interact with controllers of one or more subnetworkswhich provide the necessary network connectivity.

In the preferred architecture, the network includes two subnetworks, abackbone subnetwork and an access subnetwork. The backbone subnetwork,preferably an ATM switch network, provides point-to-point connectivityfor interactive services. The access subnetwork provides local loopdistribution of broadcast signals and interactive service signals fromthe backbone subnetwork. Also, the Level 1 Gateway preferably conductssignaling communications with the DET's, the level 2 gateways and one ormore controllers of the subnetworks through the backbone subnetworkinstead of through the X.25 packet switched system used in the VideoDial Tone Network of FIG. 1. The principal functionalities of the Level1 Gateway discussed above, however, will generally remain the same andwill be substantially enhanced by addition of new functionalities asdiscussed later.

Network Overview

FIG. 3 is a high level functional diagram of a network providingbroadcast and interactive broadband services, through an a backbonesubnetwork 15₁ and an access subnetwork 15₂, under control of theinventive Level 1 Gateway 19.

The preferred embodiment illustrated in FIGS. 5 to 9 and discussed laterutilizes asynchronous transfer mode (ATM) transport in the backbonenetwork and RF transport technology for local loop distribution to thesubscriber's terminal through the access subnetwork. The Level 1 Gatewayfunctionality of the present invention, however, applies to otherbroadband networks using other transport technologies in the backbonenetwork and the access subnetwork.

FIG. 3 therefore provides a generic illustration of the video dial tone(VDT) transport network 15. As shown, the network 15 comprises abackbone subnetwork 15₁ and one of several possible access subnetworks15₂. The access subnetwork distributes broadcast programming to customerpremises devices 17 and dynamically provides transport for interactiveservice related signals to and from the customer premises devices 17.The backbone subnetwork 15₁ provides two-way communications between IMTVservice VIPs and nodes of the access subnetwork 15₂.

Certain digital program signals carried on the network may be encryptedin the access subnetwork, using encryption technology and key codes.Details of specific encryption algorithms and the key codes forencrypting and decrypting the signals are well known to those skilled inthe art and familiar with the relevant patents and literature. Preferredprocedures for downloading the key codes to the elements in the accesssubnetwork which encrypt the signals and the decoders in the CPE deviceswill be discussed later.

The enhanced VDT network 15 may be considered as including a separatecontrol subnetwork 15₃, however, the principle component of that networkis the Level 1 Gateway 19. The control subnetwork 15₃ will also includesome means to store a variety of information relating to servicesprovided through the network, VIPs and VIUs for use by the Level 1Gateway 19, either in a separate data storage system as shown, or instorage within the computer system serving as the Level 1 Gateway 19.The backbone subnetwork and the access subnetwork each include acontroller which is the single point of contact between the Level 1Gateway 19 and the respective subnetwork. Specifically, the backbonesubnetwork 15₁ includes a backbone controller 16₁, and the accesssubnetwork includes an access controller 16₂.

For example, in the network embodiment shown in FIG. 4 of the parentapplication, pending patent application Ser. No. 08/304,174 filed Sep.12, 1994, the loop distribution interface and associatedhybrid-fiber-coax distribution system constituted an access subnetwork.The video manager then served as the access subnetwork controller. Thebackbone network included the ATM switch, and the backbone subnetworkcontroller was the permanent virtual circuit (PVC) controller.

In the network illustrated in instant FIG. 3, a number of broadcastvideo information providers (VIPs) operate one or more broadcast sources11, which have a one-way connection (downstream) to various nodes of theaccess subnetwork 15₂. The broadcast signals may be analog or digital ora combination of both, as discussed below. In the preferred embodiment,each digital source supplies a number of broadcast programs to theaccess subnetwork 15₂ in ATM cell form.

A source 11 will supply the program signals, e.g. ATM cells containingdigitized broadcast information for a broadcast service, to the network15 at all times that the service is to be available through the network.For video services, for example, the original source video material isdigitally encoded and compressed, and the digital video information ispacketized in ATM cells for transport through the network 15. The ATMcells can represent service signals for broadband services (e.g. video),audio services (e.g. radio) or data services (e.g. text).

In the preferred embodiment, the VIU's customer premises equipment (CPE)17 consists of a Digital Entertainment Terminal (DET) 17₁ which includesa network interface module (NIM) 17₂ adapted to connect the DET to thespecific type of loop distribution plant servicing the subscriber'spremises. For broadcast services, the DET 17₂ typically is able toselect and process any digital or analog channel broadcast through theaccess subnetwork 15₂ to which the customer subscribes.

For premium services requiring some form of network connection control,e.g. on-line selection of a pay-per-view event, the subscriber'sterminal or CPE device 17 sends a request signal to the Level 1 Gateway19 within the control subnetwork 15₃, as illustrated by the separatedotted line from the DET to the Level 1 Gateway 19.

In response to the instructions from the Level 1 Gateway 19, the accesscontroller 16₂ causes the access subnetwork 15₂ to supply programsignals for the requested broadcast service to the customer's CPE device17. The routing functionality of the access subnetwork for broadcastservices depends on the structure thereof. In the preferred embodiment,enabling reception of a broadcast program requires identifying the RFchannel carrying the program to the DET and supplying certaininformation needed to decode the program signals to the DET 17₁ and/orthe NIM 17₂. The Level 1 Gateway 19 will store usage data identifyingthe requested service in its associated database, for billing purposes,for audience surveys, maintenance purposes, etc.

For interactive multi-media television (IMTV) type services, the systemwill include a number of interactive service video information providers(VIP's) systems 25. As discussed in more detail later, each IMTV VIP 25operates some form of source or server for transmitting informationdownstream through the network 15 to a terminal which has requested aninteractive session with the particular VIP. Each IMTV VIP 25 alsooperates a control element, referred to as a level 2 gateway, whichprovides two-way signaling communications to the Level 1 Gateway 19 andprovides two-way signaling communications through the network 15 to theCPE devices 17 subscribers who have established interactive sessionswith the VIP. The level 2 gateway controls operations of the server inresponse to instructions from the Level 1 Gateway 19 and variousinformation input by subscribers through their respective CPE terminaldevices 17.

The signaling communications for the IMTV VIP's 25 may go through aseparate signaling network, as in the embodiment of FIG. 1, but in thepreferred embodiment the signaling communications for those VIP's goesthrough the backbone subnetwork 15₁. The IMTV VIP's will typically offerbroadband interactive services, such as video on demand, video basedhome shopping and video games, but these VIP's may offer otherinteractive services, such as interactive text services and interactiveaudio services (e.g. voice mail and audio on demand).

To establish a session with one of the interactive VIP's 25, a useroperates his or her terminal device 17 to interact with the Level 1Gateway 19 to identify the particular VIP of choice. Once the subscriberselects the VIP 25, the Level 1 Gateway 19 instructs the backbonesubnetwork 15₁ and the access subnetwork 15₂ to establish at least abroadband downstream link between the VIP's server and the particularsubscriber's CPE device 17 and provides any necessary information to theIMTV VIP's equipment.

If the system uses a separate signaling network, the Level 1 Gateway 19or the VIP's control equipment (level 2 gateway) would initiate aparallel two-way signaling link from the VIP's control equipment to thesubscriber's terminal, in a manner similar to the operation in thenetwork of FIG. 1. If the signaling rides on the backbone subnetwork15₁, the instructions from the Level 1 Gateway 19 to the controllers 16₁and 16₂ could also establish the signaling link between the VIP's level2 gateway and the subscriber's terminal device 17. Once the broadbandand signaling links are up and running, the subscriber interacts withthe VIP's equipment to obtain a particular desired service, e.g. toorder a video of choice.

FIG. 4 depicts a functional hierarchy stack of the software and networkoperations relating to the Level 1 Gateway in the preferred networkimplementation. As shown in FIG. 4, the network functionality can beconceptually divided into six block elements, service data functions,service control functions, session management functions, connectionmanagement functions, element management functions and actual elementfunctions. The service data functions, service control functions,session management functions, and connection management functions allare performed by software application modules running on the Level 1Gateway 19.

In the diagram of FIG. 4 and the following description thereof, "VIU"refers to the video information user or subscriber.

The service data functions application module provides real time accessto the customer and the network. The service data functions also includeaccumulation and maintenance of service related data. In particular, theservice data includes VIP related data and subscriber or VIU (videoinformation user) related data. The VIP related data function storesservice profile information (VIP identification code, sever portinformation, level 2 gateway signaling address, type of DET's servicedby each VIP's equipment, etc.) for each VIP and makes that informationavailable to the service control functionality as needed. The VIUrelated data function stores subscriber service profile information foreach end user and makes that data available to the service controlfunctionality as needed. The user profile data may include informationsuch as the type of DET, DET identifications (if necessary), globaladdress and/or billing telephone number, signaling address, etc.

The second functional level performed by an application software modulerunning in the Level 1 Gateway 19 relates to the service controlfunctions of the network. This is the level at which most of theinteractions with the VIP and the subscriber take place. As shown, theseinteractions between the Level 1 Gateway and the DET include personaloptions, event ordering, service activation, profile and subscriptionmanagement, CPE software management, VIP directory/menu, authorizationmanagement and session agent.

Personal options permits a subscriber to customize certain video dialtone related options through direct interaction with the Level 1 Gateway19. Examples of personal options set up and modified through thisinteraction with the Level 1 Gateway include PIN numbers, VIP menus, andhours of service. Another personal option might allow the subscriber tospecify certain times of the day or week when the network should permitaccess to certain broadcast or interactive services.

The event ordering interaction permits a subscriber to interact with theLevel 1 Gateway to specify a pay-per-view event to be broadcast in thefuture which the user wants authorized in advance, to insure on-timereception. As part of this function, the Level 1 Gateway maintains eventrelated data for the various broadcast VIP's and their respective eventsand interacts with the subscriber through the DET to inform thesubscriber of upcoming events and receive event order inputs from thesubscriber. The Level 1 Gateway 19 also signals the DET 17₁ at theappropriate time to at least notify the user and may instruct the DET toturn on and/or select the appropriate channel and digital video slot toreceive and display the ordered event.

The service activation function permits the user to specify variouslevels of broadcast service that are to be provided to the subscriberthrough the subscriber's DET's. The profile and subscription managementfunction is similar and related to the service activation function. Theprofile and subscription management application provides an automatedmeans for the user to alter the user's profile and subscriptioninformation stored in the Level 1 Gateway. This software applicationsubmodule communicates relevant change information to necessary systems,e.g. CPE software management, session management and/or networkmanagement, to implement desired changes. For example, this applicationsubmodule can be used to change scrambling, encryption or interdictionstatus of a broadcast channel for the user. As another example, throughthe profile and subscription management function the Level 1 Gatewaywould interact with the subscriber to add service for a new DET at thesubscriber's premises.

Under the CPE software management function, the Level 1 Gateway willdownload software needed by the DET for a particular call, if needed.Examples of such software downloaded from the Level 1 Gateway includebroadcast channel maps, signaling protocol versions, and completesignaling protocols. Also, if the DET 17₁ is not capable ofcommunicating with a VIP selected by the subscriber, the Level 1 Gateway19 can download a translation program to the DET to convert messagescompatible with the DET to and from message formats compatible with theVIP's equipment. Depending on the type of downloaded software, thedownloading may occur only once at the time of installation,periodically or on an as-needed basis.

The VIP directory/menu application submodule presents an interface tothe end user to navigate among video dial tone service features offeredthrough the network. This application submodule presents the user withoptions, receives selections from the users and translates selectionsinto service requests for processing by the session agent functionapplication submodule. Options available to the user, in an initialpreferred embodiment, include: establishing an internal session (withinLevel 1 Gateway) with a profile/subscription application, establishingan internal session (within Level 1 Gateway) with an eventscheduling/ordering application, establishing an external session (witha level 2 gateway) to a particular interactive VIP, help functions,terminate a current session and resume an earlier interactive session(one of two maximum). For some VIP's, the VIP directory/menu applicationsoftware may also provide menus of the particular VIP's services. Forexample, if one VIP offered video on demand, home shopping and homebanking services, that VIP might have the Level 1 Gateway present theuser with a menu of those services before actually proceeding toestablish the session with that VIP's equipment. The VIP would haveaccess to the menu data to update that data as needed.

The authorization management application submodule provides a genericauthorization control capability that can be re-used across differentones of the services applications. This functionality would be separateand in addition to the PIN number functionality offered by the personaloptions. The authorization management application software, for example,might be used to define a pass code to permit a subscriber access to theevent scheduling/ordering application, particularly if the subscriber ispaying for the ordered event by credit card.

The session agent function or application submodule of the Level 1Gateway actually translates a subscriber's request to communicate with aparticular VIP and that VIP's acceptance of the call from the subscriberinto a command to the next level to take actions to set up the desiredcommunication session. Specifically, the agent application maintainsstatus information for each user session, whether the session has anexternal end-point to a VIP or an internal end point within the Level 1Gateway (e.g. to the directory/menu application, the eventscheduling/ordering application, etc.). The session agent applicationresponds to various requests from the user, from the VIP, or from theapplication within the Level 1 Gateway to establish, modify or breakdowna session and provides appropriate instructions to the session managerapplication to actually establish, modify or breakdown sessions. Inturn, the session agent functionality receives feedback from the sessionmanger as to the results of the instructions and in response theretoprovides reports to the end users and to the VIP's. The session agentapplication submodule controls which sessions are active at any time,from an end user perspective, and which if any sessions become activeupon termination of an existing active session. For applicationsinternal to the Level 1 Gateway, the session agent also effectivelywakes up and terminates the relevant application. Another feature of thesession agent application is that it provides a mechanism to notify theuser of events, e.g. network failures. Finally, the session agentfunctionality provides billing related information to the billingsystem.

As seen from the above discussion, the service control functions providecommands to the next lower level functionality to start making and/orterminating the communication connections through the network. The nextlower level functionality, the session management functions breaks downeach session into each end-to-end connection required for that session.The session management software application module maintains addressesof the network interface points of all of the VIP servers and eachuser's DET. The session management module functionality responds torequests from the session agent application to establish and breakdownsession, relates user and VIP identifiers to the appropriate addressesfor their respective network interface points and converts eachindividual session between two network interface points into theindividual connection links needed for that session. The sessionmanagement application module then provides appropriate requests to thenetwork connection management functionality to establish and break downthe individual connections which make up a session, and the sessionmanagement application module receives feedback on the results of thoserequests. The session management application also monitors the entiresession to maintain status information regarding active systemtopologies, and this application collects the actual usage informationand passes that information to the billing system.

The connection management application module also has access toaddresses of the network interface points of all of the VIP servers andeach user's DET as well as the addresses of the entry and exit points ofeach subnetwork. The connection management application breaks down eachend-to-end connection identified by the session management functionalityinto all of the network subsystem elements needed to complete theconnection. This application coordinates with the subnetwork controllers(backbone controller 16₁ and access controller 16₂) to determineavailability of necessary transport capability and issues requests withend point addresses for each network subsystem (e.g. from an IMTV VIPand from the access subnetwork controller) for the requisiteconnectivity. Using this methodology, the connection managementapplication module responds to requests from the session managementfunction to establish and break down a connection between interfacepoints of a VIP and an end user by providing corresponding requests tothe relevant subnetwork controllers. The connection managementapplication also receives feedback from the element managementfunctionality applications performed by those controllers and notifiesthe service management application of events, such as failures.

Each element management function maps the course or route through therespective network subsystem and provides instructions to the relevantnetwork elements to produce the actual connections. In the preferredembodiment, ATM element management is the function of the PVC controllerwhich corresponds to the backbone controller 16₁ of FIG. 3. Routingthrough the access subnetwork in the hybrid fiber-coax distributionnetwork to the individual terminal devices 17 is controlled by an accesssubnetwork controller discussed in more detail below.

In the preferred implementation, the ATM element managementfunctionality maintains a view of allocated ATM connections andavailable resources across the ATM portion of the network. The backbonesubnetwork controller functionality responds to commands from theconnection management application of the Level 1 Gateway to establishpaths through the backbone subnetwork. In the ATM subnetworkimplementation, the PVC controller provides instructions to the ATMswitching elements to establish the connections. The backbone subnetworkcontroller functionality also collects event and status data andaggregates traffic statistics through the backbone switching elements.Another function of the backbone subnetwork element managementapplication is to notify the connection management application ofevents, such as failures, in the backbone subnetwork.

The access subnetwork management applications performed by the accesssubnetwork controller respond to requests from the connection managementapplication of the Level 1 Gateway 19 to establish both downstream videocommunications and one-way or two-way signaling communications over thehybrid fiber-coax distribution system.

The last element of the functional hierarchy stack depicted in FIG. 4relates to the actual element functions. For the ATM implementation ofthe backbone subnetwork, this function is preformed by the ATM switch orswitches which will provide switched ATM virtual circuits for point topoint connections from VIP's servers to ports of the access subnetwork.As part of its operations, the PVC controller will collect trafficstatistics from the ATM switch(es) and monitor the status of thebackbone switch fabric and of individual connections. Each ATM switchreceives and responds to commands from the ATM portion of the elementmanagement function, i.e. from the PVC controller, to establish and teardown ATM connections and provides notice of various events (includingfailures) to the element management function.

The actual element function for routing through the hybrid fiber-coaximplementation of the access subnetwork to individual DET's is performedby allocation of channel resources and control of the encryption anddecryption operations in that subnetwork, as discussed in more detailbelow with regard to FIGS. 5 to 9.

Specific Network Architecture

FIG. 5 discloses a distributed network architecture for a broadband datafull service type enhanced video dial tone network according to apreferred embodiment of the present invention. FIGS. 6 to 9 provide moredetailed illustrations of portions of the network of FIG. 5.

The network of FIG. 5 includes a Level 1 Gateway 1108, an ATM subnetwork1106 and an access subnetwork. In this implementation, the accesssubnetwork includes at least the broadcast ring 1102, the video networkhub offices (VNHs) 1104, a plurality of local video access nodes (LVANs)1112, and a plurality of local loop distribution (LLD) networks 1124providing communications between customer premises 1126 and the servingLVAN 1112. The broadcast consolidation section (BCS) 1100 may also beconsidered as a part of the access subnetwork. The network interfacemodule (NIM) portion of the user terminal preferably also is an elementof the access subnetwork.

As in the network overview of FIG. 3, each subnetwork includes asubnetwork controller. For the ATM subnetwork 1106, the controller is aPVC controller 1248, shown in FIG. 9. The access subnetwork controller1240 also is shown in FIG. 9.

The physical structure of the Level 1 Gateway 1108 in the network ofFIGS. 5 to 9 is essentially the same as in the earlier embodiment exceptthat the interfaces are different. Essentially, the Level 1 Gateway 1108is a UNIX based computer having adequate processing power and datastorage capacity. In this embodiment, the Gateway 1108 has an interfacefor two-way ATM cell based communication through the ATM backbonesubnetwork. In an initial implementation, the Level 1 Gateway 1108 has adirect data communication interface to the PVC controller 1248, as shownin FIG. 9. In that implementation, the PVC controller 1248 interfaces tothe programmed control elements of the ATM hub switch 1252 through anX.25 packet data interface.

In a future implementation, the PVC controller 1248 will have an ATMinterface to the hub switch 1252. Through this interface, the PVCcontroller 1248 will transmit instructions to the hub switch 1252 andreceive confirmations and various reports from the hub switch. The Level1 Gateway 1108 will also communicate with the PVC controller 1248 usingATM through the ATM subnetwork, in a manner similar to thecommunications between that gateway and the access subnetwork controller1240. The ATM interface between the PVC controller 1248 and the hubswitch 1252 also will permit that controller to communicate with ATMaccess switches under its control.

The PVC Controller 1248 and the access subnetwork controller 1240 alsoare computers having the appropriate network interfaces and softwareprogramming. The ACC 4000 is a computer system programmed to administerencryption keys and NIM network addresses in the hybrid-fiber-coax typeaccess subnetwork. Computers similar to the ACC 4000 are used today inCATV headend systems, but those computers also run software relating toother CATV operations, e.g. billing.

The network shown in FIG. 5 is arranged to centralize signal processingtasks within a LATA in order to minimize hardware. At the same time, thedisclosed network provides maximum flexibility by providingcommunications to local access nodes, each serving a local loop ofsubscribers.

The network disclosed in FIG. 5 includes a broadcast consolidationsection (BCS) 1100, a broadcast ring 1102, a plurality of video networkhubs (VNHs) or video access nodes (VAN) 1104 coupled to the broadcastring 1102, an ATM backbone subnetwork 1106, a Level 1 Gateway 1108, avideo data control center 1110, and a plurality of video end offices orlocal video access nodes (LVANs) 1112. According to the preferredembodiment, each of the video network hubs 1104 will serve acorresponding plurality of up to six (6) LVANs 1112. In addition, thepreferred embodiment will provide up to sixteen (16) VNHs 1104 servicedby the ring 1102.

The broadcast consolidation section 1100 serves as the broadcasthead-end and network interface for broadcast VIPs 1114 and 1116. Thebroadcast consolidation section 1100 is adapted to receive broadcastvideo data in any format that may be convenient for the VIP.Specifically, the broadcast consolidation section 1100 includes adigital encoder 1118 to convert baseband analog video signals, forexample from VIP 1116, into a digitally-compressed DS-3 signal stream.Alternatively, the digital encoder 1118 could be replaced with an MPEG-2encoder to provide compressed MPEG-2 packets at a DS-3 rate.

The broadcast consolidation section 1100 also includes an ATM cellmultiplexer 1120, also referred to as an ATM edge device, which performspolicing and rate conversion of incoming ATM streams. The ATM edgedevice 1120 performs policing of ATM cell streams by monitoring the datarate of incoming data streams from VIPs. For example, if the VIP 1114has subscribed by contract to transmit a data stream at 3 Mbits/s to thenetwork, the ATM edge device 1120 will prohibit or drop ATM cells thatare transmitted above the subscribed bit rate; in this case, a 6 Mbits/sstream would be rejected as an unauthorized rate.

In order to maximize the data-carrying capacity of the ATM streamssupplied to the ATM edge multiplexer 1120, the VIP 1144 and the VIP 1116will preferably supply digital video signals in compressed MPEG-2 formatthat are transported in ATM cells.

The MPEG-2 standard, recognized in the art, provides a standardizedformat for packetizing the compressed audio and video information andfor transporting other data. Under the MPEG-2 standard, incomingindividual video signals and related audio signals are encoded andpacketized into respective Video and Audio Packetized Elementary Streams(PES). The video and audio PES's from one or more sources of videoprogramming may be combined into a transport stream for transmission orstorage.

Each frame of compressed program information (audio, video or data) isbroken down into a series of transport packets. Although video framescan vary in length, the transport packets have a fixed 188 byte size.Thus, different frames are broken down into different numbers of MPEGtransport packets. For example, for a 6 Mbits/sec encoding system, agroup of frames consisting of a total of 15 frames for one-half secondof video breaks down into approximately 4000 transport packets.

Transport stream packets consist of a 4 byte header section, an optionaladaptation field and a payload section. The header information includes,inter alia, a synchronization byte, a variety of different flags used inreconstruction of the video frames, and a thirteen bit programidentification (PID) number. PID value 0 is reserved as an indicationthat the packet includes program association table data. PID value 1 isreserved for identification of packets containing conditional accessdata, such as encryption information. Other program identificationnumbers are utilized to identify transport packets with the programsource from which they originate.

Periodically, the transport packet for each program will also include aprogram reference clock (PRC) value within the optional adaptationfield. For example, the PRC may be present in only 10 out of every 4000video transport packets.

MPEG-encoded packets can be output in a variety of data rates. Forexample, the MPEG-2 compression standard is able to encode a videoprogram to a 6 Mbits/sec bit stream, and packetize up to four (4) 6Mbits/sec bit streams into a single 27 Mbits/sec stream. For otherlower-rate data streams carrying text or signaling information, up toeight (8) 3 Mbits/sec bit streams can be packetized into a single 27Mbits/sec stream, and up to sixteen (16) 1.5 Mbits/sec bit streams canbe packetized into a single 27 Mbits/sec stream. Alternatively, six (6)analog audio-video program signals can be processed in parallel toprovide six (6) 6.312 Mbits/sec MPEG-2 packets that can be output on asingle 45.736 Mbits/sec DS-3 bit stream. In addition, a synchronousoptical fiber such as SONET at 155 Mbits/sec (DL-3) can carry twenty(20) 6 Mbits/sec MPEG streams.

Thus, each of the VIPs 1114 and 1116 are preferably able to compress upto six (6) NTSC analog audio/video program signals in parallel into anMPEG-2 format. The resulting six (6) MPEG-2 packet streams with theappropriate overhead information are combined into a single MPEG-2stream at 45 Mbits/sec (DS-3). The MPEG-2 streams are then convertedinto an ATM stream before transport to the ATM edge multiplexer 1120.The ATM streams may be output at a 45 Mbits/sec (DS-3) rate for carryingup to six (6) MPEG-encoded programs, or on an optical fiber at 155Mbits/sec (OC-3) for carrying up to twenty (20) MPEG-encoded programs.

Asynchronous transfer mode or "ATM" transport is an advanced, high-speedpacket switching technology. In ATM, information is organized into cellshaving a fixed length and format. Each cell includes a header, primarilyfor identifying cells relating to the same virtual connection, and aninformation field or "payload". According to the preferred embodiment, a53 byte ATM cell includes a cell header consisting of 5 bytes and apayload consisting of 48 bytes of payload data. The ATM cell headerinformation includes a virtual path identifier/virtual circuitidentifier (VPI/VCI) to identify the particular communication each cellrelates to. For example, the virtual path identifier (VPI) may be usedto identify a specific VIP 1114 or 1116, and the virtual channelidentifier (VCI) may be used to identify a specific output port of thatVIP. In such a case, for example, VIP 1114 could be assigned a VPI valueof "65", and VIP 1116 could be assigned a VPI value of "66". Thus, theVPI/VCI value of the ATM cell header could be used to identify thesource of the ATM stream.

In ATM, transfer is asynchronous in the sense that the recurrence ofcells that contain information from any particular sender is notnecessarily periodic. Each device using the ATM network submits a cellfor transfer when they have a cell to send, not when they have anassigned or available transmission time slot. However, the ATM cells mayride in synchronous slots on a high-speed time division multiplexedmedia, such as a SONET optical fiber. ATM allows any arbitraryinformation transfer rate up to the maximum supported by the ATMnetwork, simply by transmitting cells more often as more bandwidth isneeded.

During the ATM conversion process, the individual programs from the MPEGpackets are broken into cell payloads and VPI/VCI header information isadded to map the programs into ATM virtual circuits in the correspondingoutput cell stream. As noted above, each MPEG packet consists of 188bytes, whereas each ATM cell includes 48 bytes of payload data. Thepreferred mapping scheme uses two different adaptations. The firstadaptation maps one 188 byte MPEG packet into five ATM 48 byte cellpayloads. The second adaptation maps two 188 byte MPEG packets intoeight ATM 48 byte cells payloads.

MPEG packets of 188 bytes map efficiently into ATM cells if pairs ofpackets are mapped into 8 cells. However, a delay is imposed on mappingof a first cell while waiting for the second cell in the pair. Tominimize jitter during decoding, the packets carrying the PRC need to beencoded and transported quickly. To avoid delaying first packetscontaining a PRC while processing a second packet, the ATM multiplexer1215 maps first packets containing a PRC immediately, using the fivecell adaptation procedure. As noted above, the PRC is typically presentin only 10 out of every 4000 packets. Also, at least some of those 10packets likely will arrive as the second packet of a pair. Consequently,only a very small number of packets are mapped using the less efficient5-cell adaptation.

As noted above, each cell of a particular stream will have a headerwhich contains a virtual path identifier/virtual circuit identifier(VPI/VCI) to identify the virtual circuit that the cells pertain to. AllMPEG packets for a given program, whether video, audio or data, will bemapped into ATM cells having the same VPI/VCI. Conversely, cells havinga given VPI/VCI will contain data corresponding to only one identifiedprogram. Thus, each ATM cell carrying video information for a specifiedprogram from a video information provider can be identified on the basisof its corresponding VPI/VCI.

As noted above, the VIP 1114 and/or VIP 1116 may transmit the ATM cellson a SONET optical fiber at an OC-3 rate, or may transmit the ATM cellsat a DS-3 rate. The transmission of ATM cells in an asynchronous DS-3signal may require a common clock reference in order to ensure framealignment. In a preferred network implementation, the network interface1100 receives the DS-3 signal carrying six MPEG-2 channels in ATM cellformat from the ATM VIPs in accordance with a physical layer convergenceprotocol (PLCP). The PLCP is a framing structure used to ensure that ATMcells are aligned with respect to a corresponding video frame, eventhough there may exist drifting of a start and end of a typical DS-3frame. Specifically, the PLCP references a DS-3 header and identifiesthe location of each ATM cell with respect to the DS-3 header. Since theDS-3 frame contains a maximum of twelve ATM cells, the PLCP notes thelocation of each of the cells 1-12 with respect to the DS-3 header.Therefore, even though there may be DS-3 frame drifting, the PLCPensures alignment, from a cell perspective, between the cell layer andthe DS-3 frame so that each of the twelve ATM cells within each DS-3frame can be located.

The ATM edge multiplexer 1120 acts as a groomer for multiple VIPterminations to prevent extraneous data from using network resources.The ATM streams from the VIPs 1114 and 1116 may arrive in either DS-3format or via optical fiber in OC-3 format. The ATM edge device 1226provides a grooming function, whereby ATM cells are analyzed, on acell-by-cell basis, to determine if they should be transmitted on thenetwork. Specifically, ATM cell headers that do not have valid data aredropped from the ATM stream. Each valid ATM cell is mapped on the basisof its corresponding VPI/VCI header either to a valid OC-3 output portof the ATM edge device 1120, or possibly to a null port. In addition,the ATM edge device 1120 maps the ATM idle bits containing noinformation that are present in the ATM stream from the VIPs to a nullport, thereby rejecting the received ATM idle bits.

The ATM cell mapping, also referred to as cell translation, enables DS-3ATM cell streams that are transmitted at less-than-full capacity to bemapped onto at least one OC-3c stream operating at full capacity. Thisis particularly effective when, for example, optical fibers used by theVIPs 1114 or 1116 to transport DS-3 ATM streams using optical fiberswill not be operated at capacity, especially when VIPs using the opticalfibers have varying bandwidth requirements over time. The ATM edgeprocessor 1120 processes all incoming DS-3 bit streams received thereby,and maps the DS-3 bit streams into at least one condensed, or combinedbit stream for transmission through the network. Specifically, theincoming DS-3 and OC-3 streams are supplied to correspondingfirst-in-first-out (FIFO) input buffers internal to the 1120 to supplythe ATM cells to an internal multiplexer on a cell-by-cell basis. Theinternal multiplexer outputs the translated cells preferably to OC-3output buffers for synchronous transmission on optical fibers 1121.Since the ATM cells are output at a rate of 155 MHz (OC-3), each of theoptical fibers 1121 carry up to twenty (20) MPEG programs at 6Mbits/sec. Thus, the ATM edge processor is able to fully load thedownstream optical fibers 1121 thereby to fully load the capacity of thenetwork. A more detailed description of the ATM cell multiplexer 1120 isfound in copending and commonly-assigned application Ser. No.08/380,744, filed Jan. 31, 1995, the disclosure of which is incorporatedin its entirety by reference.

According to the preferred embodiment, the digital encoder 1118 outputsa digitally encoded data stream in DS-3 format (45 Mbits/s), and the ATMedge multiplexer 1120 outputs an ATM stream in OC-3c format (155.5Mbits/s), to a SONET multiplexer 1122. The SONET multiplexer 1122multiplexes the DS-3 and OC-3 signals from the digital encoder 1118 andthe ATM edge multiplexer 1120 and outputs the consolidated broadcastdata onto the unidirectional optical fiber broadcast ring 1102 operatingat an OC-48 format (2488.3 Mbits/s). In other words, the SONETmultiplexer 1122 may receive a plurality of OC-3 optical fibers 1121,either from the ATM edge multiplexer 1120 or a plurality of suchmultiplexers. In addition, the SONET multiplexer 1121 may receive aplurality of DS-3 signals from a corresponding plurality of encoderssuch as digital encoder 1118. The SONET multiplexer 1122 buffers theOC-3 and DS-3 input signals and multiplexes the input signals togetherat a rate of 2488.3 Mbits/sec. An exemplary SONET multiplexer is theFT-2000, manufactured by AT&T.

The broadcast ring 1102 is arranged as a drop-and-continue (D/C) SONETtransport to service up to sixteen (16) VNHs 1104. Additional VNHs maybe serviced by overcoming the distance limitations of the opticalfibers. Although the broadcast ring 1102 preferably has one OC-48 fiber,the broadcast ring 1102 may be modified to include 2 or more OC-48fibers for additional traffic, or for bidirectional traffic around thering. As discussed below in detail with respect to FIG. 6, each VNH 1104receives the broadcast ATM streams from the broadcast ring 1102,converts the ATM streams to MPEG-2 streams that are transmitted on an RFcarrier, and adds local broadcast information (e.g., over-the-airaccess, public access channel) before transport to the associated LVANs1112 as RF signals, preferably via optical fibers.

Each LVAN 1112 receives the consolidated broadcast data from thecorresponding VNH 1104. The LVAN 1112 combines the received RF signalsfrom the VNH 1104 with any data transmitted by the ATM backbonesubnetwork 1106 addressed to a subscriber served by the LVAN 1112. Theresulting RF signal is transmitted via a local loop distribution network1124 to a number of customer premises 1126 (only one shown forconvenience). As discussed below with reference to FIG. 8, the localloop distribution 1124 is preferably arranged as a hybrid fiber-coaxdistribution system, although an ADSL system or a fiber-to-the-curbsystem may be substituted.

The equipment at the subscriber site 1126 includes a network interfacedevice (NID) for splitting the RF signal, a network interface module(NIM) for decoding encrypted data from the network and routing MPEG datastreams, and a digital entertainment terminal (DET) for decoding theMPEG data streams passed by the NIM. Additional details regarding theNIM and the DET are discussed below with reference to FIG. 8.

As shown in FIG. 5, each LVAN 1112 has access to the ATM backbonesubnetwork 1106 in order to send and receive network signalinginformation to and from the Level 1 Gateway 1108 and/or the video datacontrol center 1110. For example, a video information user (VIU) whowishes service on the network via one of the LVAN's 1112 may request theservice either by calling a network business office by telephone or byrequesting a Level 1 Gateway session from his or her customer premises1126 in order to perform on-line registration. As discussed in detailbelow, the ATM backbone subnetwork 1106 provides signaling informationbetween the LVAN 1112 serving the VIU, the Level 1 Gateway 1108 and thevideo data control center 1110 in order to activate the VIU on thenetwork, or to update the services available to the VIU.

The ATM backbone subnetwork 1106 also is adapted to communicate with theVIPs 1114 and 1116 in order to perform account management between theVIPs, the Level 1 Gateway 1108 and the video data control center 1110.For example, the VIP 1114 may supply a request to the Level 1 Gateway1108 for a desired bandwidth in order to broadcast a pay-per-view eventat a predetermined time. The Level 1 Gateway 1108 and the VIP 1114 willdetermine the appropriate VPI/VCI header to be loaded onto the ATMstream to be supplied to the ATM edge multiplexer 1120 of the broadcastconsolidation section 1100. The Level 1 Gateway 1108 will inform thevideo data control center 1110 of the scheduled event, as well as theVPI/VCI of the video data stream. The Level 1 Gateway 1108 will alsocommunicate with the VIPs 1114 and/or 1116 via the ATM backbonesubnetwork 1106 in order to maintain up-to-date lists of authorized VIUsto receive the selected VIP services.

Finally, as discussed in detail below with respect to FIG. 9, the VIP1116 may conduct an interactive (IMTV) session with a VIU via the ATMbackbone subnetwork 1106 and the LVAN 1112 servicing the specific VIU.Although not shown in FIG. 5, the VIP 1116 can conduct IMTV sessionswith a VIU using a level 2 gateway and an IMTV server internal to theVIP 1116. The level 2 gateway communicates with the Level 1 Gateway 1108of the network, to receive and process requests for IMTV sessions thatinclude routing information. The IMTV server outputs broadband data forthe VIU as an ATM cell stream to the ATM backbone subnetwork 1106.

Communication between the network and the VIP 1116, as well as betweenthe network and the VIU, is established under control the Level 1Gateway 1108. From the VIU perspective, a user will communicate with thenetwork via the Level 1 Gateway 1108 in order to select the VIP 1116 foran IMTV session. In a network providing access to multiple IMTV serviceproviders, the user wishing to establish an IMTV session identifies theprovider of choice to the Level 1 Gateway 1108 by inputting controlsignals to the user's DET, which supplies the appropriate signalsupstream from the customer premises 1126 to the Level 1 Gateway 1108 viathe corresponding LVAN 1112 and the ATM backbone subnetwork 1106. Inresponse, the Level 1 Gateway 1108 controls the broadband routingfunctionality of the network to establish a downstream broadbandcommunication link and a signaling link between the provider and theuser.

The Level 1 Gateway 1108 receives notification of the status ofbroadband communications links as they are being set up and duringongoing communications through those links. The Level 1 Gateway 1108therefore can inform a subscriber when a requested session can not beset up with a selected service provider, i.e. because the provider'sserver ports are all busy or because the subscriber is not registeredwith the particular provider or due to some technical problem. The Level1 Gateway 1108 also recognizes when an established link develops a faultor is interrupted and can stop accumulating usage or billing dataregarding that link. The Level 1 Gateway 1108 can also notify thesubscriber and/or the service provider of the failure.

The Level 1 Gateway 1108 will also store various information relating toeach subscriber's services and control service through the networkaccordingly. At least some of this stored data is accessible to thesubscriber through a direct interaction with the Level 1 Gateway 1108.For example, the user can identify certain service providers to theLevel 1 Gateway 1108 and define an authorization code or identificationnumber which must be input before the network should provide a sessionwith the user's equipment 1126 and the identified providers.

Many of the functions of the Level 1 Gateway 1108 relate principally toset up, monitoring and billing for point-to-point type interactivesessions. As noted above, however, a number of the Gateway functionsalso apply to broadcast services. For example, the interaction with theLevel 1 Gateway 1108 can be used to advance order upcoming broadcastpay-per-view events. At the time for the event to begin, the Level 1Gateway 1108 will transmit appropriate notice to the orderingsubscriber's terminal. In response, the terminal may display the noticeto the subscriber or the terminal may automatically turn on and/or tuneto the appropriate communication link through the broadcast network toobtain the ordered event. The interactive features of the Level 1Gateway 1108 also permit subscribers to specify limitations they wish toplace on their broadcast services, e.g. total number of hours of usagewithin some defined interval and/or time of day/week of permitted usage.The Level 1 Gateway 1108 will then control the broadcast network and/orthe subscriber's terminal in accord with the limits defined by thesubscriber.

FIG. 6 is a block diagram of the network showing in detail a VNH 1104 inaccordance with the preferred embodiment of the present invention.

As shown in FIG. 6, each VNH 1104, also referred to as a broadcastheadend node, comprises a SONET multiplexer 1130 that receives the OC-48signal from the broadcast ring 1102. The SONET multiplexer 1130 is adrop-and-continue (D/C) multiplexer that "drops" the OC-48 signal fromthe broadcast ring 1102 for local processing, and outputs the OC-48signal to "continue" on the broadcast ring 1102. The SONET multiplexer1130 converts the OC-48 signal to obtain the OC-3 ATM stream and thedigitally-encoded (DS-3) baseband video signal output by the ATM edgemultiplexer 1120 and the digital encoder 1118, respectively, as shown inFIG. 5.

The structure of ATM cells is generally recognized in the art. The ATMcell includes a header section and a payload section. In addition, theATM cell may include additional overhead sections that provideadditional vendor-proprietary features, such as priority levelassignments, or forward error correction. The first byte of the headersection includes a 4-bit GFC word which provides access control. Thefirst byte of the header section also includes the lower four bits of an8-bit virtual-path identifier (VPI). The second byte of the headersection includes the upper four bits of the VPI and the first four bitsof a 16-bit virtual circuit identifier (VCI). The third byte includesthe next eight bits of the VCI. The fourth byte of the header sectionincludes: the last four bits of the VCI; a 3-bit payload type (PT); anda cell loss priority (CLP) bit. The fifth byte of the header section 410includes an 8-bit header error check (HEC) word. The CLP bit is used tomanage traffic of ATM cells: in the event of network congestion, cellswith CLP set to 1, indicating a lower priority, are dropped before cellswith CLP set to 0.

The specific format of the ATM cell is described, for example, in theATM User Network Interface Specification, Version 3.0, published by TheATM Forum, Mountain View, Calif., also published by Prentice Hall, thedisclosure of which is incorporated in its entirety by reference.According to the ATM User Network Interface Specification, the values0-18 for the VCI are reserved; therefore, any ATM cell having valid datamust have a VCI value greater than "18". Thus, prior to transmission onthe network, the ATM edge multiplexer 1120 identifies ATM cells that donot have VCI values greater than "18" as idle cells that do not carryvalid data.

Referring to FIG. 6, the SONET multiplexer 1130 extracts the ATM cellsby analyzing the input stream in 5-byte increments in order to check theheader/error/check (HEC) sequence for valid ATM data; if the SONETmultiplexer 1130 verifies the HEC sequence, the 53-byte ATM cell isextracted and supplied to an ATM packet demultiplexer (APD) 1134.Although FIG. 6 shows only one ATM packet demultiplexer 1134, in thepreferred embodiment the VNH 1104 includes a plurality of thedemultiplexers.

The VNH 1104 includes an analog portion that receives analog basebandvideo signals from the VIPs, from a Public Access Channel (PAC)broadcast source 1135, and from Over-the-Air (OTA). Specifically, theSONET multiplexer 1130 outputs the DS-3 encoded baseband video signal toa DS-3 analog decoder 1132, which converts the DS-3 signal back to theVIP analog baseband video signal. The VIP analog baseband video signalis output from the analog decoder 1132 to a modulator 1136, whichincludes a tuner to mix the VIP baseband video signal from the analogdecoder 1132 onto a specific 6 MHz bandwidth RF channel. The PACBroadcast Source 1135 provides public access channel (PAC) programmingrelated to community activities as a PAC baseband analog video signal,preferably via an optical fiber. A fiber optic receiver and equalizeramplifier 1138 converts the optical signal from the PAC Broadcast Source1135 to a baseband analog PAC video signal that is supplied to amodulator 1136' for mixing to a specified 6 MHz channel.

The analog portion of the VNH 1104 also includes a plurality of antennas1140 that receive Over-the-Air (OTA) broadcast signals at VHF and UHFfrequencies. The OTA signals are supplied to an analog signal processor1142, which performs signal conditioning and modulates the OTA signalsto specified 6 MHz bandwidth RF channels. For example, the analog signalprocessor 1142 may modulate the OTA television channels 4, 7 and 9 to24, 27, and 29, respectively, in order to avoid interference with thePAC or VIP analog video channels. The VNH 1104 may also include anotherantenna 1140' that receives FM radio signals and supplies the FM signalsto an FM radio signal processor 1143. The signal processor 1143 outputsthe FM radio signal within a specified RF band, preferably the FM radioband, to the RF combiner 1144.

Thus, the video signals output by the modulator 1136 and the analogsignal processor 1142 are analog RF video signals at different 6 MHz RFchannel frequencies, as well as the FM signals output by the signalprocessor 1143. The analog signals output from the FM radio signalprocessor 1143, the modulator 1136 and the analog signal processor 1142go to an RF combiner 1144. The RF combiner 1144 is a passive combinerwhich combines the VIP, PAC and OTA analog video signals and the FMradio signal into a single RF signal. The video portion of the combinedRF signal includes a plurality of analog 6 MHz channels. Thus, the VIPanalog video signals, the PAC analog video signals and the OTA analogvideo signals can be received and viewed using a conventional televisionset, without the need for a digital entertainment terminal. Thus, theseanalog video signals could make up a basic video service analogous tothe type offered by contemporary cable-TV companies. A video dial tonenetwork subscriber can also receive FM radio broadcasts using aconventional FM receiver.

The RF combiner 1144, however, enables passive combining of differentbaseband analog video signals, as opposed to known cable-TV systems,which require a rewire of modulators whenever a change was made inchannel allocation. Thus, changes in the channel allocation in thedisclosed embodiment can be made merely by reprogramming the modulator1136 and the analog signal processor 1142. As discussed below, the RFcombiner 1144 is also adapted to combine RF signals carrying thecompressed digital video signals from the VIP.

The digital portion of the VNH 1104 receives the compressed VIP digitalvideo signals from the recovered OC-3c ATM stream output from the SONETmultiplexer 1130. The OC-3c ATM stream is output from the SONETmultiplexer 1130 to one of several ATM packet demultiplexers (APD) 1134(only one shown for convenience). The APD 1134 performs ATM processingand repacketizes the MPEG-2 packets on the basis of the VPI/VCI headersof the incoming ATM streams. Specifically, the ATM packet demultiplexer1134 buffers cells until it finds a cell having an ATM cell AdaptationUnit (AAU) value of "0" in its header (first cell) and another cellhaving an AAU value of "1" in its header (last cell). The ATM packetdemultiplexer 1134 counts the number of cells from first to last todetermine the type of adaptation used to map cells.

If the ATM packet demultiplexer 1134 has captured five cells, thereceiver pulls out the payload data and uses the CRC data to check forerrors. If there are no errors, the original MPEG packet isreconstructed from the appropriate bytes of payload data from the firstfour cells. Similarly, if the receiver has captured eight cells, thereceiver pulls out the payload data, does the CRC based error check, andif there are no errors, the original pair of MPEG packets isreconstructed from the appropriate bytes of payload data from the eightcells.

The reconstructed MPEG packets are assigned new PID values based on theVPI/VCI value of the ATM stream that carried the MPEG packets. Thismapping of a new PID values in response to the VPI/VCI of the ATM streamis based upon a translation table loaded into the ATM packetdemultiplexer 1134 by the access subnetwork controller 1240, via a theATM subnetwork and a signaling path 1146 (Ethernet or the like),discussed in detail below.

In a typical example, there are at least three PID values for packets ofa particular program, a first PID value for packets containing video, asecond PID value for packets containing audio and another PID value fora packet containing a program map. There often are more than three PID'sassociated with programming from one source. For example, there could bea data channel associated with the program which would include data forclosed captioning for the hearing impaired and/or related controlsignaling information. There could be a number of audio elementarystreams, for example, carrying respective different languages. Theprogram map, in turn, specifies the PID values for the various packetscontinuing video, audio and/or data from the particular source.

In a combined MPEG packet stream carrying packets for two or moreprograms, the PID values for each program will be unique. For example,the program map for HBO might be found in packets corresponding to PID132; the program map for TMC might be found in packets identified by PID87 and so forth. The program map for HBO in the packet with PID 132would then identify the PID numbers for the actual packetized elementarystreams (PES) for the video, audio and data (if any) channels associatedwith the HBO program. The program map for TMC in the packet with PID 87would then identify the PID numbers for the actual packetized elementarystreams (PES) for the video, audio and data (if any) channels associatedwith the TMC program.

In the received OC-3c streams received by the APD 1134, the packetscarried in the ATM cells have PID values assigned by the respectiveVIP's encoding equipment. The MPEG-2 standard also requires that apacket stream containing packets relating to one or more programsincludes a program association table in a packet identified by PID 0.The program association table maps each program source with the PIDvalue associated with the program map related to that source. In accordwith the standard, the VIPs' encoders will construct the MPEG packetstreams for each program to include a PID 0 packet containing theprogram association table. The program streams also include a packetidentified by a PID value in that table containing the program map forthat program. Thus, the APD can capture the program association table inpacket PID 0 to identify the PID value for the program map from thesource of programming and can capture the program map to identify thePID values applied by the source encoder to identify the data (if any),video and audio for the particular program. Alternatively, the APDscould be preprogrammed with the relevant PID values inserted by theVIPs' encoders. The translation table in the APD 1134 is used to mapeach PID value in the reconstructed packets of a particular program intoa new PID value which is unique at least within the output stream of theparticular output port of the APD, as a function of the VPI/VCI value ofthe received ATM cells.

For example, assume for convenience that the HBO program arriving at theAPD consists of video packets with a PID value of 17 and audio packetswith a PID value of 19. The program map is contained in a packetidentified by PID value 3, and the program association table in packetPID 0 identifies PID `3` for the program map. The APD recognizes all ofthe packets as originating from a single program source based on theVPI/VCI of the ATM cells and maps the PID values into new unique values,e.g. 27 for video and 37 for audio. The APD also constructs a newprogram map containing the new PID values for video and audio andinserts the new map in a packet identified by PID value of 132.

The APDs provide five broadband (27 Mbits/s payload) output rails.Assuming 6 Mbits/s programs, the APDs combine four MPEG-2 packetsstreams of four such programs for output on each broadband rail. TheAPDs will combine more programs into each output transport stream if theprograms use lower bit rates, e.g. 1.5 or 3 Mbits/s. If strictcompliance with the MPEG-2 standard is necessary, the APDs can constructand insert a new PID 0 packet into each such broadband output stream.The PID 0 packet output in each broadband transport stream would includea new program association table for that transport stream, i.e.identifying the PID value of the program maps for the four or moreprograms contained in the broadband transport stream output.

As discussed in more detail below, reception of a particular digitalprogram requires that the CPE terminal device know the RF channeltransporting the program and at least one PID value associated with theprogram. Preferably, the PID value is that of the program map for theparticular desired program, e.g. 132 in the above HBO example. Althoughthe transport stream may include the program association table in packetPID 0 to insure compliance with the standard, the downloading of the PIDvalue for the program maps eliminates processing time delays in channelsurfing required to capture PID 0 packets.

The ATM packet demultiplexer 1134 outputs the reconstructed MPEG packetson one of five 27 Mbits/s digital signal paths or `rails` to acorresponding modulator/multiplexer 1150. U.S. Pat. No. 5,231,494 toWachob, the disclosure of which is incorporated herein in its entiretyby reference, teaches quadrature phase shift keyed (QPSK) modulation ofa plurality of video, audio and data signals into a single data streamwithin a standard six MHz channel allocation for transmission over aCATV type distribution network. Using 64 QAM (quadrature amplitudemodulation), 4 channels of 6 Mbits/s MPEG encoded digital videoinformation can be modulated into one 6 MHz bandwidth analog channel.Similarly, 16 VSB (vestigial sideband) yields 6 channels of 6 Mbits/sMPEG encoded digital video information modulated into one 6 MHzbandwidth analog channel. Each RF modulator produces a 6 MHz bandwidthoutput at a different carrier frequency.

In the illustrated preferred embodiment, the modulator/multiplexer 1150is a Quadrature Amplitude Modulator (QAM) operating at 64 QAM, wherebymedia access control (MAC) is performed to ensure proper timing of theresulting time-division multiple access (TDMA) signal. Thus, each of thefive 27 Mbits/s digital signals are 64 QAM modulated and multiplexedinto an IF signal, which is upconverted into a specific 6 MHz channel.The QAM/multiplexer 1150 outputs the 6 MHZ channels to the RF combiner1144 for combining with the other 6 MHz RF signals. The RF combiner 1144thereafter outputs the combined RF signals to a lightwave transmitter1154, which outputs the combined RF signals on an optical fiber 1156 fortransmission to the local video access nodes 1112.

Although the disclosed network is designed to transport digitalbroadband data for high data-rate applications such as video, thenetwork is also able to transport low data-rate information to bebroadcast from an information provider to the VIUs. In such a case, theATM packet demultiplexer 1134 will determine from the VPI/VCI that thereceived data is a low-rate data signal; consequently, the ATM packetdemultiplexer 1134 will output the low-rate data signal in MPEG formatto a quadrature phase-shift keyed (QPSK) modulator 1152, which modulatesthe low-rate data signal for RF transmission after passing through theRF combiner 1144. The low data rate transmission may carry text orsignaling information from a VIP in some way relating to one or moreservices offered by that VIP.

Thus, the APDs 1134 map ATM cells into MPEG packets for both broadbandservices and narrowband information (e.g. signaling). The APD 1134 isprogrammed to map VPI/VCI values in the cells into certain PID values inthe resultant packets. Based on the VPI/VCI value, the APD 1134 alsowill route the packets to an identified one of its outputs. The APD 1134outputs broadband related packets and associated in-band signaling onone of five 27 (payload) Mbits/s output rails going to one of the 64 QAMmodulators 1150. The APD 1134 outputs packets related to downstream outof band signaling on a separate 1.5 Mbits/s (payload) rail going to aQPSK 1152.

The signaling path 1146 coupled to the components of the VNH 1104 ispreferably an Ethernet communication path. Although not shown in detail,the Ethernet signaling path 1146 provides signaling and control signalsto each of the components of the VNH 1104. The Ethernet signaling path1146 communicates with the video data control center 1110 via the ATMbackbone subnetwork 1106 in order to provide the operating status ofeach of the components of the VNH 1104. Specifically, the Ethernetsignaling path 1146 provides upstream signaling data to an ATM router1148, which packets the Ethernet signals in ATM cell format, provides aVPI/VCI header for the intended destination of the Ethernet signal, andoutputs the ATM stream onto the ATM backbone subnetwork 1106. The ATMbackbone subnetwork 1106 routes the ATM stream from the ATM router 1148of the VNH 1104 to a corresponding ATM router 1244 at the video datacontrol center 1110 (FIG. 9). Preferably, the ATM backbone subnetwork1106 routes ATM streams between the VNH 1104 and the video data controlcenter 1110 along dedicated virtual paths. The ATM router 1244 at thevideo data control center 1110 receives the ATM stream, reassembles theEthernet signals, and outputs the Ethernet signals on its local Ethernetbus with a destination corresponding to the VPI/VCI of the ATM stream.The ATM virtual circuit to the video data control center 1110 is atwo-way circuit and carries instructions from the video data controlcenter 1110 back to the components of the VNH 1104.

FIG. 7 discloses one of the network local video access nodes (LVAN) 1112according to a preferred embodiment of the present invention. Thedisclosed LVAN 1112 is one of a plurality of LVANs that is distributedthroughout the network service area in order to provide service tocustomers. In early implementation stages, however, it is anticipatedthat the first deployed LVAN 1112 may be collocated with the VNH 1104 inorder to service a limited service area. Later deployed LVANs 1112 willbe located remotely from the VNH 1104.

One of the electrical-to-optical converters 1154 in the video networkhub (VNH) 1104 transmits the combined RF spectrum signal over an opticalfiber 1156 to one of the local video access nodes (LVNs) 1112. As shownin FIG. 7, the LVAN 1112, also referred to as a video central office orvideo end office, includes an optical-to-electrical (O/E) receiver 1160that converts the optical RF signal from the optical fiber 1156 to anelectrical RF signal. The RF signal output from the O/E receiver 1160 issupplied to an equalization amplifier 1162 for signal conditioningbefore RF combination by an RF combiner 1164, similar to the RF combiner1144 shown in FIG. 6. The combined RF signal is output from the RFcombiner 1164 and reconverted to an optical signal by theelectrical-to-optical (E/O) transmitter 1166. The E/O transmitter 1166supplies the optical signal to the local loop distribution via opticalfibers 1168.

If desired, the LVAN 1112 may also combine the RF signal from the VNH1104 with a local PAC broadcast signal supplied by a local PAC source1135. In such a case, the local PAC broadcast signal is received by afiber optic receiver and equalizer amplifier 1138', which supplies theconditioned local PAC broadcast signal to the modulator 1136' forconversion to an RF signal at an available 6 MHz channel beforecombining by the RF combiner 1164.

The LVAN 1112 also provides signaling traffic between the VIU and thenetwork, as well as broadband traffic for interactive multimediatelevision (IMTV) sessions. Specifically, the LVAN 1112 includes a SONETmultiplexer 1170 that receives optical signals carrying ATM streams fromthe ATM backbone subnetwork 1106 via a unidirectional OC-48c opticalfiber 1172. The SONET multiplexer 1170 converts the OC-48 signal intoOC-3c signals carrying ATM streams. The ATM cells transport IMTV trafficand VIU signaling traffic from the VIPs and the network, respectively.The OC-3c signal is input to an APD 1134, which repacketizes the ATMcells into MPEG format and assigns PID values based on the VPI/VCI valueof the received ATM cells. The APD 1134 preferably is identical to theATM packet demultiplexer 1134 in the VNH 1104 and performs the packetreconstruction and PID value mapping in exactly the same manner asdiscussed above.

The APD 1174 determines from the VPI/VCI value whether the ATM cellstransport broadband data such as video, or narrowband data such as VIUsignaling information or text data. The APD 1174 outputs the broadbanddata in one of five 27 Mbits/s MPEG streams to one of five 64-QAM MACMUXmodulators 1176. In addition, the APD 1174 outputs the narrowband dataas an MPEG stream to a QPSK modulator 1178, which modulates the MPEGstream carrying narrowband data for combining by the RF combiner 1164.The 64-QAM MACMUX modulator 1176 outputs the modulated broadband signalto an RF upconverter 1180, which outputs the modulated broadband signalon an available 6 MHz RF channel for combining by the RF combiner 1164.Thus, the RF combiner outputs a combined RF stream carrying 6 MHzchannels of information to the VIUs from different sources, includingbroadcast VIPs, PAC Broadcast Source 1135', IMTV VIPs, and networkcontrollers for signaling traffic.

An additional feature of the present invention is that the informationoutput by the RF combiner 1164 is not limited to broadband video frombroadcast or IMTV VIPs, and signaling traffic from the network. Rather,since the VIU is able to transmit information to the LVAN 1112 via aoptical fiber upstream signaling link 1184, the LVAN 1112 may be adaptedto transmit to the VIUs information from any data source. For example,reference numeral 1182 denotes other data sources that can use thedisclosed network for transport to the VIU: a user could remotely accessa LAN source 1182a using the upstream signaling link 1184 for two-waycommunication; the network could control power to the user's DET, oralternatively work in conjunction with electric utilities to read auser's electric meter using a power management controller 1182b; or areserved port 1182c could be set aside for future interactive dataapplications. In such a case, the data is output from one of the sources1182 to a corresponding RF modulator 1186 before combining by the RFcombiner 1164.

Upstream signaling from the VIU is received from the upstream signalinglink 1184 by an E/O receiver 1188, which outputs the multiplexed RFsignal from the VIUs to an RF splitter 1190. The RF splitter 1190 splitsthe RF spectrum and outputs the split RF spectrum on predeterminedsignal paths. For example, a predetermined RF channel will containsignaling information to be supplied from the VIU to the Level 1 Gateway1108, such as a request for new service, or a request for an IMTVsession with a VIP via a Level 2 gateway. This VIU signaling informationwill be supplied to a demodulator 1192 to demodulate the signalinginformation off the RF carrier. The demodulator 1192 will output thedemodulated VIU request to one of thirteen (13) network controllers (NC)1194, each of which processes VIU requests and identifies thedestinations for the requests from a specified group of CPE devices. TheNC 1194 passes each VIU request to an ATM router 1196, which receivesinputs from the network controllers, packetizes the VIU request in anATM cell stream, adds a VPI/VCI header to identify the destination ofthe request, and outputs the ATM stream onto the ATM backbone subnetwork1106. The processing of the VIU request is discussed in more detailbelow.

As discussed above, the upstream signaling link 1184 may provideupstream signaling data for the other data sources 1182. For example,the RF splitter 1190 outputs an RF signal at a predetermined band to oneof the demodulators 1198 corresponding to the devices 1182. Thedemodulators 1198 remove the RF carrier signal and output thedemodulated signal to the corresponding device 1182.

As discussed above with respect to FIG. 6, the VNH 1104 includes anEthernet control network to control the components of the VNH 1104.Similarly, the LVAN 1112 comprises an Ethernet system 1200 forcontrolling the components of the LVAN 1112. As discussed in detailbelow with respect to FIG. 9, the Ethernet system 1200 communicates withthe network via the ATM router 1196, which passes Ethernet messagesbetween the Ethernet system 1200 and remote Ethernet systems via the ATMbackbone subnetwork 1106.

FIG. 8 discloses an exemplary implementation of the local loopdistribution network 1124 shown in FIG. 5 in accordance with thepreferred embodiment of the present invention. Although the local loopdistribution 1124 shown in FIG. 8 is a hybrid-fiber coax system, onehaving ordinary skill in the art will appreciate that other local loopdistribution systems may be used, such as Asymmetrical DigitalSubscriber Loop (ADSL), Fiber-to-the-Curb, or direct fiber to the livingunit. One preferred alternative utilizes a switched digital videofiber-to-the-curb access subnetwork such, as shown in FIG. 3 of theparent application.

As shown in instant FIG. 8, the combined RF signal output from the RFcombiner 1164 is converted to an optical signal by the E/O transmitter1166 and output to the local loop distribution 1124 on the opticalfibers 1168. Generally, the optical signal will be provided to aplurality of optical fibers via an optical splitter, preferably amaximum of four optical fibers per combiner 1164. Each optical fiber1168 carries the combined analog RF signal to a fiber node 1202.According to the preferred embodiment, each fiber node 1202 serves onebroadcast service area (BSA) of up to 500 homes passed.

The fiber node 1202 comprises an O/E transceiver 1204 that providestwo-way conversion between optical and electrical RF signals transmittedto and received from a plurality of terminal amplifiers 1206. Eachterminal amplifier 1206 outputs the downstream electrical RF signal ontoa coaxial cable 1208. The coaxial cable 1208 is designed to pass onehundred twenty five (125) homes. Specifically, a tap 1210 is installedalong the 1208 for each living unit that wishes activation on thenetwork. A coaxial drop cable 1212 is wired between the 1210 and thecustomer premises 1126. Thus, assuming each home receives a tap 1210 forservice on the network, each coax cable 1208 will service up to 1125homes.

As shown in FIG. 8, the customer premises 1126 includes a networkinterface device (NID) 1214, a network interface module (NIM) 1216, anda digital entertainment terminal (DET) 1218. The NID 1214 receives thecoax drop 1212 and splits the RF signal into four coax signal paths.Each home or living unit 1126 is preferably allocated a capacity of fourdigital entertainment terminals 1218 (DET's). Each coax feed is suppliedto the NIM 1216, which demodulates the downstream RF signal at auser-specified channel frequency. If the demodulated RF signal is ananalog video signal from an analog source (such as the PAC 1135), theNIM 1216 passes the baseband analog video signal directly to thetelevision set without further processing by the DET 1218.

If, however, the NIM 1216 receives an MPEG encoded signal, the NIM 1216will de-encrypt the 27 Mbits/s MPEG encoded signal using a keydownloaded from the network's ACC-4000 (described in detail below). Uponde-encrypting, the NIM 1216 supplies the 27 Mbits/s MPEG encoded signalto the main portion of the DET 1218 for further processing to present aselected program to the user.

The NIM 1216 also demodulates a downstream signaling channel carryingsignaling data in MPEG packets. From the signaling channel, if the MPEGencoded signal has a PID value corresponding to the NIM address, the NIM1214 processes the MPEG stream as NIM signaling data. If, however, thePID value corresponds to the DET address, the NIM 1214 extracts the datafrom the MPEG stream and outputs that data to the DET CPU.Alternatively, the NIM and DET may have a single PID value address, inwhich case, data within the signaling packet indicates whether themessage is for the NIM or the main portion of the DET.

The DET of the present invention is an open interface device in that itinteracts with equipment of a large number of service providers (oftenreferred to as "VIPs") to offer users a wide array of video andinteractive multi-media services. The digital entertainment terminal(DET) is a programmable device to which different individual videoinformation providers (VIP's) can download applications software, and atleast one VIP (the VIP selling the DET) can download all or a part ofthe operating system. In non-volatile memory (ROM and non-volatile RAM),the DET will store a loader program and an operating system. The loaderprogram and operating system in the ROM and the non-volatile RAM willinclude sufficient programming to control initial communications anddefine interfaces and drivers, e.g. for graphics to define the base linefunctionality of the DET for all service applications the DET will run.

The NIM 1216 provides the interface necessary for the DET 1218 tocommunicate with the local loop distribution system 1124. The structureof the NIM 1216 is dependent on the local access technology (in thiscase, hybrid-fiber coax), the NIM 1216 provides standardized controlsignals to and from the DET 1218, Consequently, the main portion of theDET 1218 can be implemented as a generic consumer product that isindependent of the local access technology, whether it is hybrid-fibercoax, ADSL, satellite receiver, or fiber to the curb.

Although not shown in FIG. 8, the NIM 1216 presents two connections tothe DET 1218, a high bit rate broadband connection and a low bit ratesignaling connection. The broadband connection is a one-way downstreamonly connection, but the low-bit rate signaling connection is a two-wayconnection.

The NIM 1216 includes a frequency agile demodulator for processing thedownstream narrowband transmissions. The demodulated data may relate toNIM functions or to functions of the main portion of the DET 1218. TheNIM also includes a frequency agile QPSK modulator, to permittransmission of upstream signaling information over the coaxial cable onspecified RF channels not used for downstream transport. The mainportion of the DET can supply messages to the NIM for such upstreamtransmissions, and under certain circumstances, the NIM's internalcontrol processor can transmit upstream messages in this manner.

As discussed below, the network assigns each NIM 1216 to a defaultchannel for downstream reception and a default channel for upstreamtransmission. The QPSK demodulator and the QPSK modulator within the NIMcan also shift to other channels allocated on a dynamic basis, e.g. toprovide signaling for IMTV services requiring more bandwidth than isavailable through the default channels.

The main portion of the DET 1218 receives selected MPEG streams from theNIM 1216, and decompresses selected MPEG packets in order to recover theoriginal digital signal. If the digital signal is narrowband signalinginformation for the DET 1218, the signaling information is supplied tothe DET microprocessor as raw data, for appropriate processing. If thedigital signal is broadband information, the NIM 1216 supplies the MPEGpacket stream to the main portion of the DET via a broadband (e.g. 27Mbits/s) interface. The DET determines whether the data in the broadbandMPEG packets is digital video or audio data or other broadband data, andsupplies the data through respective MPEG decoders to the television orto the DET microprocessor, accordingly.

The DET 1218 is adapted to receive and store downloaded controlsoftware. The DET 1218 can establish a link to the network via a Level 1Gateway session to receive operation systems code, default channel maps,and permissions tables in order to receive broadcast services frommultiple VIPs. In some cases, the DET may also establish a point topoint link to a VIP's interactive equipment. For broadcast services, theDET captures a cyclically broadcast application, for example navigationsoftware.

The DET 1218 captures and processes a digital channel based on the RFchannel and the PID value associated with the program map for theparticular source program. As noted above, the program map specifies thePID values for packets continuing video, audio and/or data from theparticular source. For example, HBO might be one of four digitalprograms carried in RF channel 53, and the program map for HBO might befound in packets corresponding to PID 132. The program map for CBS inthe packet with PID 132 would then identify the PID numbers for theactual packetized elementary streams (PES) for the data (if any), videoand audio channels associated with the HBO program.

Once the DET 1218 identifies and captures the programming map, the MPEGdecoder section can extract the video elementary stream, the audioelementary stream(s) and any associated data stream for decoding of theprogramming.

Within an identified video elementary stream, video sequence headersdefine things like frame rate, resolution, and the coordinates on thescreen where display of the image should begin. Such coordinates areuseful, for example, in defining pictures within a picture when multiplepictures are superimposed. In each video stream packet, after the videoheader sequence, the packet contains the actual video syntax which, inthe case of MPEG, includes the normal frames associated with videocompression, such as I frames and B frames, etc., in MPEG.

In the preferred network implementation, the NIM 1216 stores thedecryption keys that are supplied from the APD 1134 via the downstreamsignaling channel output on the 64-QAM MACMUX modulator 1176 and the RFupconverter 1180 in FIG. 7. The NIM uses those keys to decrypt selectedprograms before supplying the program signals to the main portion of theDET. Thus, a user's DET 1218 receives only authorized MPEG data streams,thereby improving network security and reducing the ability ofunauthorized users to access other video programming.

A more detailed description of the structure of the DET and NIM and theoperations thereof involved in downloading applications software andoperating system changes into the DET are disclosed in copendingapplication Ser. No. 08/380,755, filed Jan. 31, 1995, incorporatedherein in its entirety by reference.

FIG. 9 is a block diagram illustrating the relation of the ATM backbonesubnetwork 1106, the video data control center 1110, and a Video DialTone (VDT) control center including the Level 1 Gateway 1108 shown inFIG. 5. As shown in FIG. 9, the video data control center 1110 includesan access subnetwork controller 1240, an ACC-4000 1242, and an ATMrouter 1244 for sending and receiving ATM cell streams to and from theATM backbone subnetwork 1106.

The access subnetwork controller 1240 communicates with the elements inthe VNHs 1104 and the LVANs 1112 via the ATM router 1244, dedicatedvirtual circuits through the ATM subnetwork 1106 and the ATM routers1148, 1196 and associated Ethernets 1146, 1200 in the respectiveoffices. The ACC 4000 1242 communicates with the APDs 1134, 1174 in theVNHs 1104 and the LVANs 1112 via the ATM router 1244, dedicated virtualcircuits through the ATM subnetwork 1106 and the ATM routers 1148, 1196and associated Ethernets 1146, 1200 in the respective offices. Forexample, through such communications, the access subnetwork controller1240 downloads PID value mapping information based on the VPI/VCI valuesof incoming cells to the respective APDs, and the ACC 4000 1242downloads encryption keys to the APDs. The ATM router 1244 and the ATMbackbone network 1106 also permit the access subnetwork controller 1242to communicate with the Level 1 Gateway 1108 of the present invention.

The VDT Control Center 1246 comprises the Level 1 Gateway 1108 and aPermanent Virtual Circuit (PVC) controller 1248. Although not shown, theVDT Control Center 1246 includes a corresponding ATM router torepacketize the ATM cells and supply the messages to the Level 1Gateway.

The PVC controller 1248 is the external controller for the ATMsubnetwork 1106. The ATM subnetwork 1106 includes at least one hub ATMswitch 1252, as shown in FIG. 9. In future implementations providingIMTV services from larger numbers of VIPs to larger numbers of VIUs, theATM subnetwork 1106 will include the hub switch 1252 and a number of ATMaccess switches (not shown). The access switches will provideconnections from the hub switch to particular nodes of the accesssubnetwork.

As shown, the PVC controller 1248 connects directly to the ATM hubswitch 1252. In one implementation, this is an X.25 connection. Whenupgraded to interact with multiple ATM switches, the PVC controller 1248has an open interface to all of the ATM switches to allow communicationwith and control of switches produced by various manufactures. In thepreferred multi-switch embodiment, an ATM signaling connection from thePVC controller 1248 provides communications with the programmedcontroller of the hub switch itself and provides virtual circuitconnections through the hub switch to the programmed controllers of thevarious ATM access switches. Although not shown in FIG. 9, the ATM hubswitch 1252 may also provide a dedicated permanent virtual circuit forthe communications between the Level 1 Gateway 1108 and the PVCcontroller 1248.

The PVC controller 1248 interfaces to the network operations supportsystem (OSS) 1109, the Level 1 Gateway 1108 and the one or more switchesof the ATM subnetwork 1106. The PVC controller 1248 serves as the singlepoint of contact between the Level 1 Gateway 1108 and the ATM backbonesubnetwork 1106. All signaling and control messages to and from the ATMsubnetwork 1106 are communicated between the PVC controller 1248 and theLevel 1 Gateway 1108.

The PVC controller 1248 stores data tables defining all possible virtualcircuits through the ATM switch network. These data tables define theheader information and the particular input port and output port used toroute cells from each interactive multimedia (IMTV) service VIP to aninput point on the access subnetwork. The data tables thus define"permanent virtual circuits" (PVC's) between the providers and the inputports of the access subnetwork. The data tables within the PVCcontroller also define various dedicated circuits for communicationsbetween various controllers of the network and/or to the VIP'sequipment. The tables in the PVC controller 1248 include currentavailability data for VPI/VCI values and an ongoing record of whichVPI/VCI values are in use. Thus, at any given time the PVC controller1254 knows what VIP/VCI values are available to and can be assigneddynamically to provide requested bandwidth for each new IMTV session.

The ATM backbone subnetwork 1106 also comprises a plurality ofunidirectional SONET multiplexers 1254. Although only four (4) SONETmultiplexers 1254 are shown in FIG. 9. It should be understood that allconnections to and from the ATM switch 1252 are preferably at atransmission rate of OC-3 or OC-48.

According to the preferred embodiment, the ATM switch 1252 routes allATM streams on the basis of the VPI/VCI of the cell streams. The ATMstream virtual path is controlled by the PVC controller 1248, whichprovides switching control instructions to the ATM switch 1252 to set upthe virtual paths in the ATM switch 1252 from the source to thedestination in response to assignments from the Level 1 Gateway 1108. Inaddition, each VNH 1104 and LVAN 1112 is assigned a predeterminedvirtual path for communication with the video data control center 1110,thereby relieving management requirements by the PVC controller 1248.Upstream signaling traffic from a VIU to the Level 1 Gateway 1108 or thevideo data control center 1110 is routed along dedicated virtual paths.

The access subnetwork controller 1240 controls all routing of broadbandand narrowband data throughout the access subnetwork in response tobandwidth requirements supplied from the Level 1 Gateway 1108. Forexample, in the case of broadcast services such as pay-per-view, thebroadcast VIP 1114 may desire to broadcast broadband data to betransported by the network. As shown in FIG. 9, the broadcast VIP 1114communicates with the Level 1 Gateway 1108 via the ATM backbonesubnetwork 1106 to exchange interactive broadcast signaling informationin order to request a specified bandwidth at a scheduled time.Alternatively, the broadcast VIP 1114 may communicate with a businessoffice in the network, whereby the broadcast information is loaded fromthe business office into an OSS system 1109, and from there, into theLevel 1 Gateway 1108. The Level 1 Gateway 1108 will send an instructionto the access subnetwork controller 1240 that bandwidth is required atthe scheduled time for a specified duration. The Level 1 Gateway willspecify the logical network channel number for the channel that willcarry the event. From that information the controller 1240 can identifythe ATM stream having a VPI/VCI header value for the transmission fromVIP. The access subnetwork controller 1240 sends signaling messagesthroughout the access subnetwork to establish the bandwidth at thecorrect time: the ATM edge multiplexer 1120 receives a message that thespecified VPI/VCI is permitted to pass into the network; and the ATMpacket demultiplexer 1134 is loaded with the appropriate PID values tomap the ATM stream to an MPEG stream having a specified MPEG format. Theaccess subnetwork controller 1240 will also send an instruction to theACC-4000 1242 to send an encryption key to the ATM packet demultiplexer1134 to encrypt the program before RF transmission to the LVANs 1112.

At the customer premises as shown in FIG. 8, an authorized VIU will havedownloaded into the NIM 1216 the encryption key from the ACC-4000 1242via a control channel (broadband) or an out-of-band signaling channel.

The VIU will access the Level 1 Gateway 1108 in order to initiate anIMTV session with an IMTV VIP 1260. As shown in FIG. 9, the system ofthe IMTV VIP 1260 includes a Level 2 gateway 1262 for communication withthe Level 1 Gateway 1108 via the ATM backbone subnetwork 1106 and withthe DET 1218, and an IMTV server 1264 for outputting broadband videodata in ATM streams to the ATM backbone subnetwork 1106.

During the communication session between the subscriber and the IMTV VIP1260, the DET 1218 can transmit control signalling upstream through theATM subnetwork 1106 to the level 2 gateway IMTV VIP 1260. The level 2gateway IMTV VIP 1260 can also send signaling information, such ascontrol data and text/graphics, downstream through the same path to theDET or as in-band data included within the broadband output stream fromthe server 1264. For downstream transmission, the server 1264 willprovide ATM cells with an appropriate header. The ATM switch 1252 willroute the cells using the header and transmit those cells to the APD1134 serving the requesting subscriber 1236 for conversion to MPEGformat. In the presently preferred embodiment, the downstream signalingfrom the VIP is included as user data (in-band) as part of the broadbandMPEG packet stream transmitted to the DET from the server 1264.

Certain VPI/VCI values would be assigned and available to each IMTV VIP,and other VPI/VCI values would be assigned to the access subnetwork. Foreach session, the access subnetwork controller would pick the port andVPI/VCI value for entry into the access subnetwork, and the VIP wouldpick the output port and the VPI/VCI value to be output by itsequipment. The Level 1 Gateway supplies both port identifiers and thetwo end point VPI/VCI values as terminating and originating informationto the PVC controller as part of the request for connection through thebackbone subnetwork 1106. The PVC controller 1248 assigns VPI/VCI valueswithin the ATM subnetwork.

Each physical port of the ATM subnetwork 1106 will have more than oneVPI/VCI assigned to cells passing through that port. The PVC controller1248 stores data corresponding to each port that indicates the VPI/VCIvalues in use for each connection ID. When the Level 1 Gateway 1108requests a connection through the ATM subnetwork 1106, the PVCcontroller 1248 accesses its data tables to determine if the requisitebandwidth is available between the two identified ports. If not, the PVCcontroller 1248 returns a negative acknowledgement message indicatingthe reason for the inability to complete the requested connection. Ifthe bandwidth is available, the PVC controller 1248 provides appropriateinstructions to the switch or switches which will establish the link andprovides a confirmation reply message to the Level 1 Gateway 1108 whenthe link through the ATM subnetwork 1106 is complete.

Level 1 Gateway Communications

As outlined in the above discussion of the preferred networkarchitecture, the Level 1 Gateway 1108 will communicate with a VIU typesubscriber through that subscriber's DET 1218 and associated televisionset. The Level 1 Gateway 1108 also communicates with IMTV VIPs level 2gateways 1262. The Level 1 Gateway 1108 also communicates with therelevant subnetwork controllers, i.e. the access subnetwork controller1240 and the PVC controller 1248. As shown in FIG. 5, the ATM subnetwork1106 provides a connection to an Operations and Support System (OSS)1109. The Level 1 Gateway 1108 will communicate with the OSS 1109 for avariety of provisioning and usage accounting functions. The OSS 1109includes a number of information processing systems used forprovisioning, the video provider service center (VPSC) and one or morebilling systems, such as the CABS and CRIS systems discussed above. Tofacilitate understanding of the inventive Level 1 Gateway in the contextof the preferred network architecture, the following discussion providesa detailed explanation of the types of signaling and communications thatthe Level 1 Gateway exchanges with these other network elements.

The OSS 1109 provides a variety of information regarding VIPs and VIUsto the Level 1 Gateway 1108. For example, in the preferred networkarchitecture, the VIU information would include VIU profile information,such as the identities of VIPs from whom the VIU has subscribed forservices, the type of services subscribed to etc. The informationregarding each VIP relates to the types of services the VIP offersthrough the VDT network, e.g. number of channels, which channels providepay-per-view service, etc.

The OSS 1109 can also send requests to the Level 1 Gateway 1108 toset-up, tear down and modify connections. For example, when a new VIUbecomes a subscriber on the VDT network, the OSS 1109 provides the newsubscriber profile information to the Level 1 Gateway and instructs theLevel 1 Gateway 1108 to establish a permanent signaling connection tothe new subscriber's DET 1218. The Level 1 Gateway 1108 then interactswith the PVC controller 1248 and the access subnetwork controller 1240to establish the default signaling channel through the subnetworks,between the Level 1 Gateway 1108 and the subscriber's DET 1218. Thisprocess flow is described in more detail below in connection with FIG.11.

When a VIU subscribes to broadcast services of a particular VIP, the VIPwill identify the VIU to the OSS. The OSS 1109, in turn, instructs theLevel 1 Gateway 1108 to make the broadcast services of that VIPavailable to the particular subscriber's DET(s) 1218. The steps involvedin broadcast channel activation also appear as part of the VIUactivation process flow shown in FIG. 11.

Broadcast service VIPs typically will offer some pay-per-view services.At least some of those VIPs will provide necessary information regardingindividual pay-per-view events and VIUs who have purchased particularevents to the OSS 1109. The OSS 1109, in turn, provides the informationregarding individual pay-per-view events to the Level 1 Gateway 1108.The OSS 1109 also instructs the Level 1 Gateway 1108 to make apay-per-view event available to each purchasing subscriber's DET(s) 1218at the time of the particular event. Alternatively, the VIP's equipmentmay have a direct interface to the Level 1 Gateway 1108 to provide theevent information and purchasing subscriber identifications directly tothat Gateway.

The Level 1 Gateway 1108 transmits all usage information to the OSS 1109for processing by one or more of the billing systems. For a givenconnection, the usage information may include bandwidth and connect timeand/or an ATM cell count. For pay-per-view type services, theinformation will include an event identifier. The Level 1 Gateway 1108also sends alarm or failure information relating to specific sessionconnections between a VIU and an IMTV VIP to the OSS 1109 for processingby one or more maintenance related systems. The Level 1 Gateway 1108 mayrun its own internal diagnostic routines, in which case, the Gateway1108 would also notify the OSS 1109 of any faults or failures in thatGateway.

The OSS may include an interface, e.g. a level 2 gateway and/or server,to permit VIPs and VIUs to interact directly with the OSS. This is oneway that a VIU might modify or upgrade their VDT services. In anintegrated network providing telephone services as well as video and/ordata services (as discussed in more detail with regard to FIG. 4 in theparent case), the OSS 1109 would also serve as the operations supportsystem for telephone services. Consequently, the interaction with theOSS through the VDT network would allow VIUs on-line access to modifytheir telephone services. For this interface to the OSS 1109, the Level1 Gateway 1108 would provide notification of incoming calls to the OSSfrom VIPs or VIUs, in a manner similar to the notification provided to alevel 2 gateway operated by an IMTV service VIP discussed in more detaillater.

Alternatively, an application running in the Level 1 Gateway 1108 caninteract with the VIU through the DET 1218 to modify services providedto the VIU via the network. In that case, the Level 1 Gateway wouldnotify the OSS 1109 of the changes to service subscriptions made by theVIU.

As noted above, the Level 1 Gateway 1108 also communicates with the PVCcontroller 1248. The Level 1 Gateway 1108 transmits requests toestablish and tear down connections to the PVC controller 1248. Theserequests will identify the entry and exit ports of the ATM subnetworkand the end point VPI/VCI values of the relevant virtual circuits. Asdiscussed below, the Level 1 Gateway obtains one port identifier andassociated VPI/VCI value from the VIP's level 2 gateway 1262 and anotherport identifier and VPI/VCI value from the access subnetwork controller1240. The requests for connection also specify a bandwidth for thedesired connection. The Level 1 Gateway 1108 may also transmit some formof connection identifier to the PVC controller 1248.

In response to a connection request, the PVC controller 1248 providesappropriate instructions to the ATM hub switch 1252 and any accessswitches (not shown) needed to make the connection. Specifically, thePVC controller 1248 instructs the switch(es) to provide a virtualcircuit connection between the specified end points and to translate theinput VPI/VCI value into the output VPI/VCI value. The PVC controller1252 assigns any intermediate, VPI/VCI values used within the ATMsubnetwork itself. In this manner, the Level 1 Gateway 1108 and the PVCcontroller 1248 interact to establish virtual circuit connections, fordownstream broadband transmissions (one-way), for associated upstreamsignaling connections (one-way), and for two-way connections.

In the above discussed preferred operation, the Level 1 Gateway 1108obtained the VPI/VCI values from the endpoints (the VIP and the accesssubnetwork) and supplied those values to the PVC controller 1248.Alternatively, the PVC controller 1248 could use its mapping tables tomap the port ID information into appropriate termination and originationVPI/VCI values, or the Level 1 Gateway itself could administer andassign endpoint VPI/VCI values for each virtual connection it needs toestablish through the ATM subnetwork.

ATM switches provide bidirectional virtual circuits. However, in thevideo dial tone network, many connections are unidirectional(particularly those for the downstream broadband connections). Therequests for bandwidth can separately specify the bandwidth in eachdirection. For example, for unidirectional connections, the Level 1Gateway 1108 will specify the required bandwidth in one direction, e.g.downstream, and specify a `0` bandwidth in the other direction.

The above discussion of connection set-up and tear down by the Level 1Gateway, the PVC controller and the ATM switch(es) applies to thedownstream broadband connection from the VIP to a port for IMTVservices. The network also provides two-way signaling between the VIP'sequipment and the DET 1218. For this purpose, the ATM subnetwork canprovide a requested low bandwidth two-way virtual circuit in parallel tothe downstream broadband virtual circuit. The downstream signalinginformation would originate from a port on the VIP's level 2 gateway1262. If the downstream signaling is to appear as in-band information tothe DET, however, the ATM subnetwork will supply the downstream cells tothe same output port as for the broadband information, i.e. a port toone of the APDs 1174 in the serving LVAN 1112. The access subnetworkcontroller 1240 will instruct the APD 1174 to map both the broadband andthe downstream signaling cells into MPEG packets having specified PIDvalues and to output those packets on a specified one of the railscarrying data streams to one of the QAM modulators 1176 for transmissiontogether in an assigned downstream RF channel. The input port to the ATMsubnetwork for the upstream signaling would be a port connected to theATM router 1196 in the same LVAN 1112. The ATM subnetwork would outputthe upstream cells to an input port of the level 2 gateway 1162.

Alternatively, the downstream signaling from the VIP's level 2 gatewayto the subscriber's DET 1218 can consist of user data included in theMPEG-2 stream from the server. In this later case, the ATM subnetworkwould only establish a narrowband upstream channel to the level 2gateway for upstream signaling from the DET. In either case, the Level 1Gateway 1108 requests the signaling connection, and the PVC controller1248 instructs the ATM switch(es) to set up the portion of signalinglink through the ATM subnetwork.

In normal operation, the Level 1 gateway 1108 requests establishment ortear down of specific connections through the ATM subnetwork 1106. Whenthe ATM switch(es) perform the requested connection function, reportsthereof are provided to the PVC controller 1248. The PVC controller inturn provides confirmation to the Level 1 Gateway 1108. If necessaryresources are not available when the Level 1 Gateway 1108 requests aconnection, the PVC controller 1248 will so inform the Level 1 Gateway.

The Level 1 Gateway 1108 can request audit or status information fromthe PVC controller 1248. In response, the PVC controller 1248 can supplythe Level 1 Gateway 1108 with audit or status information relating tothe condition of ports and connections with the ATM subnetwork 1106. ThePVC controller 1248 will also provide the Level 1 Gateway 1108 alarm orfailure reports relating to specification connections through the ATMsubnetwork 1106.

The PVC controller 1248 may also provide usage information to the Level1 Gateway 1108. In particular, the ATM switch(es) and PVC controller1248 can count cells for each session connection through the ATMsubnetwork and provide the cell count to the Level 1 Gateway as usagedata. The cell count reflects the amount of data actually transmittedthrough the ATM subnetwork. For particularly bursty services, the cellcount may actually provide a more accurate representation of usage thanthe combination of bandwidth and time duration.

As noted above, the Level 1 Gateway 1108 also communicates with theaccess subnetwork controller 1240. The Level 1 Gateway 1108 transmitsrequests to establish and tear down connections to the access subnetworkcontroller 1240. Such requests may relate to IMTV connections, to makingcertain broadcast services available to a particular VIU, definingpay-per-view events and activating pay-per-view events for VIUs who havepurchased particular events, etc. In general, connection and tear downrequests identify the DET and bandwidth or throughput in bothdirections. In the presently preferred embodiment, the DET identifierwill take the form of an E.164 address.

Requests relating to broadcast services will include a channelidentifier and may under some circumstances include VPI/VCI information.As discussed in more detail below, the Level 1 Gateway 1108 will requestthat the access subnetwork controller `establish a connection` to theDET 1218 for each broadcast channel to which the VIU has subscribed.These `connections` for broadcast channels make those channels availableby enabling the DET to process each channel. Once the access subnetworkestablishes such a broadcast availability connection, the VIU can vieweach channel simply by selecting that channel through the DET 1218,unless and until the Level 1 Gateway 1108 instructs the accesssubnetwork controller 1240 to tear down the particular broadcastconnection.

The Level 1 Gateway 1108 issues requests relating to broadcast servicesto the access subnetwork controller 1240 only infrequently, i.e. when aVIU subscribes to a new broadcast service or when removing a broadcastservice from availability to a particular VIU (e.g. a VIU that no longersubscribes to broadcast services of a specified VIP or that has notbased bills for VDT services or services of the specified broadcastVIP).

Requests relating to IMTV service will include a connection identifier,VIU identifier and bandwidth. Unlike requests relating to broadcastservices, the Level 1 Gateway 1108 frequently issues requests relatingto IMTV services to the access subnetwork controller 1240, i.e. whenevera VIU requests an IMTV session.

Requests defining a broadcast pay-per-view event include an eventidentifier, start time, end time, channel and preview duration.Connection requests relating to activation of a purchased event for aparticular VIU identify the DET and the event.

When the access subnetwork controller 1240 receives a connectionestablishment request from the Level 1 Gateway 1108, the accesssubnetwork 1240 transmits certain information back to that Gateway thatother elements of the network need in order to set-up the end to endconnection. For a broadcast channel to which the VIU subscribes, the DETneeds a connection block descriptor for that channel. The connectionblock descriptor includes the network logical channel number and the RFchannel carrying the particular program. For digital services, theconnection block descriptor will also include one or more PID values(preferably the PID value for the respective program map) that the DETneeds in order to capture and begin processing MPEG-2 packets relatingto the particular program.

In the preferred embodiment, the access subnetwork controlleradministers the connection block descriptors and the VPI/VCI valuesavailable on each port of the access subnetwork.

When the access subnetwork controller 1240 receives a connectionestablishment request for an IMTV session, the access subnetworkcontroller first identifies an APD 1174 having available bandwidthcapable of supporting the requested session. The access subnetworkcontroller 1240 provides the port ID and an available one of the VPI/VCIvalues assigned to that APD 1174 to the Level 1 Gateway 1108. As notedabove, in the preferred embodiment, the Level 1 Gateway 1108 forwardsthe port identifier for the APD 1174 and the assigned VPI/VCI value tothe PVC controller 1248.

The APD 1174 is preprogrammed by the access subnetwork controller 1240to map ATM cells having the VPI/VCI value into MPEG packets havingparticular PID values and supply those packets through a specific one ofits output rails for RF transmission on a particular channel. The accesssubnetwork controller 1240 therefore knows the connection blockdescriptor corresponding to the bandwidth it assigned to the requestedIMTV session. The access subnetwork controller 1240 supplies thatconnection block descriptor back to the Level 1 Gateway 1108, and thatGateway forwards the connection block descriptor to the DET 1218 topermit tuning to the correct RF channel and capturing and processing ofMPEG packets from that RF channel. The discussion of FIGS. 14A and 14Bprovides a more detailed explanation of the full process flow forestablishing an IMTV session.

The Level 1 Gateway 1108 could store the connection block descriptorsfor all broadcast services. However, in the preferred implementation,the access subnetwork controller 1240 administers the connection blockdescriptors for broadcast services in a manner similar to that done forIMTV connection, albeit on a more static basis than for IMTV. When theaccess subnetwork controller 1240 receives a connection establishmentrequest for a broadcast channel from the Level 1 Gateway 1108, theaccess subnetwork 1240 knows the applicable connection block descriptorfor that channel. The access subnetwork 1240 transmits that connectionblock descriptor back to the Level 1 Gateway 1108. The Level 1 Gateway1108 in turn forwards the connection block descriptor to the DET 1218.

In response to a connection request (establishment or tear down), theaccess subnetwork controller 1240 provides appropriate instructions tothe elements of the access subnetwork needed to perform the connectionfunction. For example, for an IMTV session, the access subnetwork mayinstruct the APD 1174 to map cells having a specified VPI/VCI into MPEGpackets having specified PID values and output those packets on aspecified one of its five output rails, to thereby place the packets ina particular RF channel.

For a pay-per-view event, the access subnetwork controller provides theevent definition information to the ACC 4000 1242. The ACC 4000 in turninstructs the APD 1134 to encrypt the program using a specific key at aspecific start time. The access subnetwork controller identifies theDETs 1218 of VIUs who purchase the event, and the ACC 4000 1242 providesthe decryption key needed to decode the program to the NIMs 1216associated with those DETs 1218, at the appropriate times. At the end ofan event, the ACC 4000 instructs the APD 1134 to change the encryptionkey, thereby terminating decryption by those DETs having a now obsoletedecryption key.

In normal operation, the Level 1 Gateway 1108 requests establishment ortear down of specific IMTV connections through the access subnetwork.When the elements of the access subnetwork perform the requestedconnection function, reports thereof are provided to the accesssubnetwork controller 1240. The access subnetwork controller 1240 inturn provides confirmation to the Level 1 Gateway 1108. The level 1Gateway 1108 will time the period for confirmations, and if an expectedconfirmation is not received in the expected time period, the Level 1Gateway recognizes a fault in the access subnetwork. If necessaryresources are not available when the Level 1 Gateway 1108 requests aconnection, the access subnetwork controller 1240 will so inform theLevel 1 Gateway.

The Level 1 Gateway 1108 can request audit or status information fromthe access subnetwork controller 1240. In response, the accesssubnetwork controller 1240 can supply the Level 1 Gateway 1108 withaudit or status information relating to the condition of variouschannels and sessions through the access subnetwork. The accesssubnetwork controller 1248 will also provide the Level 1 Gateway 1108will alarm or failure reports relating to specification connectionsthrough the access subnetwork.

At the CPE, the Level 1 Gateway 1108 communicates with the main portionof the DET 1218, and through that portion of the DET, with the actualVIU operating the DET. Logically speaking, the NIM 1216 may beconsidered a part of the access subnetwork. The ACC 4000 1242communicates with the NIM 1216, whereas the Level 1 Gateway 1108 andlevel 2 gateways 1262 communicate with the main portion of the DET 1218.

Through its communications with the main portion of the DET, the Level 1Gateway 1108 sends menus to the VIU. The Level 1 Gateway 1108 alsoreceives selections and related inputs from the VIU through thiscommunication.

The communications from the Level 1 Gateway 1108 to the main portion ofthe DET carry a variety of information. For example, thesecommunications include downloading of necessary connection blockdescriptors to the DET to permit reception of broadcast channels anddynamically assigned channels carrying IMTV downstream transmissionsfrom the VIP. The Level 1 Gateway 1108 may also download applicationsprogramming and/or operations system software into the main portion ofthe DET 1218. The above incorporated copending application Ser. No.08/380,755, filed Jan. 31, 1995, provides a more detailed description ofthe software download capabilities of the DET. If certain servicesrequire the DET to recognize some form of network address, the Level 1Gateway 1108 would also transmit that address to the main portion of theDET for storage.

The subscriber input information transmitted upstream from the DET 1218to the Level 1 Gateway 1108 can relate to pay-per-view event purchases,selection of a broadcast VIP and selection of an IMTV VIP. The inputinformation may also indicate that the VIU has requested a session withan internal application running on the Level 1 Gateway 1108, for exampleto establish or modify PIN routines, customize menus, access accountinformation, modify broadcast subscriptions, etc. If the OSS 1109provides a VIU user interface, the information from the input from theVIU might also request connection to that interface through the videodial tone network.

If the subscriber request to the Level 1 Gateway 1108 identifies abroadcast service VIP, the Level 1 Gateway 1108 transmits a connectionblock descriptor of one of that VIP's channels back to the DET 1218.This connection block descriptor corresponds to a digital broadcastchannel on which the selected VIP repeatedly broadcasts customizedsoftware for downloading into the DET. Typically, the software capturedby the DET 1218 controls navigation through the particular VIP'sbroadcast services.

The Level 1 Gateway 1108 can provide its menus in two or more differentlanguages. Through an interactive session between the subscriber's DET1218 and the Level 1 Gateway 1108, the user can establish a preferencefor one language. Subsequently, the Level 1 Gateway 1108 transmits menusto that DET 1218 in the preferred language. The user also has the optionto override the preference and obtain menus in any of the otherlanguages available during each interaction with the Level 1 Gateway.

As noted above, the Level 1 Gateway 1108 also communicates with level 2gateways 1262 operated by IMTV VIPs. For example, as part of itsprocessing of a VIU's request for an IMTV session connection to a VIP,the Level 1 Gateway 1108 transmits a connection request to the chosenVIP's level 2 gateway 1262. This request includes the identity of thecalling VIU and provides the VIP with the opportunity to accept orreject the call from the particular VIU. The VIP may reject the call fora number of reasons, e.g. because all of its server equipment is busy,because the particular VIU is not a subscriber to this VIP's services,the particular VIU has not paid his bills, etc. In the preferredembodiment, the Level 1 Gateway 1108 transmits a connection request tothe chosen VIP's level 2 gateway 1262 only for IMTV type services.However, the Level 1 Gateway 1108 could transmit such a request to thelevel 2 gateway 1262 for pay-per-view services and broadcast services,if the particular VIP chose to offer their services in a mannerrequiring the VIP's acceptance or authorization before providing arequested service.

The Level 1 Gateway 1108 provides information relating to networkconditions to the level 2 gateway 1262, for specific connections to thatVIP's equipment. For example, when a VIP accepts a call and the Level 1Gateway 1108 instructs the various network elements to set up a session,the Level 1 Gateway 1108 informs the level 2 gateway 1262 of completionof the call set-up procedure, so that the level 2 gateway 1262 caninstruct the associated server 1264 to commence transmission to thesubscriber. The Level 1 Gateway 1108 will also notify the level 2gateway 1262 of failures in specific connections to that VIP'sequipment.

The level 2 gateway 1262 also provides certain information back to theLevel 1 Gateway 1108. If the VIP accepts a call from a particular VIU,the level 2 gateway 1262 transmits a server port identifier andpreferably a VPI/VCI, that will service the call. The level 2 gateway1262 will also specify the bandwidth or throughput requirement for theparticular IMTV service.

As noted above, broadcast VIPs offering pay-per-view service willprovide information about events and purchasers to the network. If theVIP has a direct connection to the Level 1 Gateway 1108, e.g. from alevel 2 gateway 1262, the VIP would supply that information directly tothe Level 1 Gateway without going through the OSS.

The Level 1 Gateway may also provide the VIP with menus and acceptselection inputs from the VIP, if the network is administered to allowVIPs to initiate calls. Such VIP initiated calls at least would go tothe OSS 1109. The preferred embodiment is adapted to provide connectionsbetween a VIP and a VIU only in response to an initial request by theVIU. However, if customer demand warrants, the Level 1 Gateway couldallow VIPs to initiate calls to VIUs from the level 2 gateways 1262. Inthat case, the Level 1 Gateway might also signal the DET 1218 and askthe VIU if the VIU will accept the call from the calling VIP.

Process Flows in the Preferred Network

The Level 1 Gateway controls initial establishment of services, e.g.provisioning, for new broadcast services offered by the broadcast VIPsand for activation of service to individual subscriber VIUs.Provisioning of a new broadcast service will be considered first. FIG.10 depicts a simplified flow of messages between various components ofthe enhanced video dial tone network during provisioning of broadcastchannels.

When a new VIP wants to offer broadcast services through the enhancedvideo dial tone network or an existing VIP wants to add additionalchannels to the VIP's services broadcast through the network, the VIPplaces an order for a number of channels with the OSS 1109 (step S101).OSS personnel will go into the field and make any necessary new physicalconnections of the VIP's equipment into the network. The OSS system 1109will provide relevant provisioning information to the Level 1 Gateway1108 (step S102).

The provisioning information transmitted to the Level 1 Gateway 1108includes a VIP ID and the number of channels as well as a channel ID andnetwork input port ID (at the Broadcast Consolidation Section (BCS)1100) for each channel. The information will also specify the type ofservice on each channel, i.e. whether the service is analog, digitalbroadcast, digital pay-per-view, enhanced pay-per-view, etc. The VIPalso specifies the desired maximum bandwidth for each new channelordered, and the OSS 1109 relays that information to the Level 1 Gateway1108. The Level 1 Gateway stores the information in a table in memory.

The Level 1 Gateway 1108 now sends a connection request to the accesssubnetwork controller 1240 via a signaling channel through the ATMbackbone subnetwork 1106 (step S103). This connection request instructsthe access subnetwork controller 1240 to activate the broadcast servicethroughout the access subnetwork. The information in the request messageincludes the VIP ID as well as the channel ID, the input port ID, theservice type (analog or digital) and the maximum bandwidth for one newchannel. For convenience, further discussion here will concentrate onactivation of a digital broadcast service.

When the access subnetwork controller 1240 receives a broadcast channelconnection establishment request from the Level 1 Gateway 1108, theaccess subnetwork 1240 identifies an APD 1134 having available bandwidthcapable of supporting the requested channel, in each of the videonetwork hubs 1104 and assigns a VPI/VCI corresponding to the availablebandwidth to the newly requested channel, as discussed in more detailbelow. The access subnetwork controller 1240 transmits a reply messageback to the Level 1 Gateway 1108 which includes at least the assignedVPI/VCI value (step S104).

The APDs 1134 in the video network hubs 1104 are essentially duplicatesof each other and have commonly assigned VPI/VCI values for the channelsthat they are to broadcast to the respective local video access nodeoffices 1112. The APDs 1134 in the video network hubs 1104 are wired inthe same manner to QAM modulators 1150 so that in each video network hub1104, the APDs 1134 and modulators 1150 output each particular broadcastprogram channel on the same RF channel. The access subnetwork controller1240 also instructs the corresponding APDs 1134 in all of the hubs 1104to map assigned VPI/VCI values into the same MPEG PID values.

The SONET drop and continue multiplexers 1130 are programmed to drop acopy of cells having a specified VPI/VCI value to the corresponding oneof the APDs 1134 in each respective video network hubs 1104. Thus, byassigning one VPI/VCI to a newly requested program channel, the accesssubnetwork controller 1240 assigns the channel to a particular APD 1134in each video network hub office 1104, and assigns the broadcasts ofthat program to an identified RF channel and PID values.

For example, in response to a request for connection of the VIP'sbroadcast service identified as network logical channel 1, the accesssubnetwork controller might assign a VPI/VCI of 1001/001. Assume now fordiscussion purposes that the VPI of 1001 identifies the first APD 1134in each video network hub 1104. The SONET mux 1130 in each video networkhub office 1104 therefore supplies a copy of each cell containing theVPI/VCI value of 1001/001 to the first APD 1134 in that respectiveoffice. The first APD 1134 in each hub 1104 in turn is programmed tooutput the reconstructed MPEG packets from the ATM cells on a specifiedone of its output ports and to include specified PID values in thosepackets.

Continuing the example, the access subnetwork controller 1240 mightprogram the first APD 1134 in each hub office 1104 to map the cellscontaining the VPI/VCI value of 1001/001 into MPEG packets containingthree PID values of (001, 007 and 010) and output those packets on thefirst output port of that APD. The APD 1134 would construct a programmap indicating that the PID values 007 and 010 identify video and audiopackets for the program and would insert that new program map in theoutput packets containing PID 001. The access subnetwork controllerknows the RF channel frequency of the QAM modulator 1150 connected tothat output port, and that frequency is the same for all of the videonetwork hub offices 1104. For example, the RF channel might correspondto CATV standard television channel 42. The access subnetwork controller1240 stores tables of connection block descriptors for all channels inthe access subnetwork. In the example, the newly established connectionblock descriptor would identify network logical channel 1, RF channel 42and PID value 001.

The reply to the Level 1 Gateway (S104) in response to the connectionrequest for logical network channel 1 would include at least the VPI/VCIof 1001/001. If the Level 1 Gateway 1108 stores tables of connectionblock descriptors, that reply message would also include the connectionblock descriptor for that channel. In the example, the connection blockdescriptor would identify network logical channel 1, RF channel 42 andPID value 001. In the preferred embodiment discussed later, the accesssubnetwork controller 1240 supplies connection block descriptors to theLevel 1 Gateway 1108 as part of a procedure for activating specificchannel services for a VIU.

The connection request and reply procedure (steps S103, S104) betweenthe Level 1 Gateway 1108 and the access subnetwork controller 1240 isrepeated for each new broadcast channel ordered by the VIP in step S101.The Level 1 Gateway 1108 in turn provides one or more acknowledgementmessages back to the OSS (step S105). For each channel, theacknowledgement identifies the VIP, the channel, the input port, and theVPI/VCI value. OSS personnel use this information to program the ATMcell mux 1120. Specifically, they obtain port and VPI/VCI informationfor each input channel the VIP will broadcast and program the mux 1120to translate the VIPs VPI/VCI values into the corresponding VPI/VCIvalues assigned by the access subnetwork controller 1240 to each newprogram.

A similar procedure can be used to provision analog channels. In thepreferred embodiment, however, the analog channels are broadcast on thebottom 40 RF channels. Rather than administer the connection blockdescriptors for these channels through the access subnetwork controller1248, the OSS 1109 can supply these to the Level 1 Gateway 1108 forstorage during initial set-up of the network.

In the above discussion, the access subnetwork controller 1240 assignedone digital broadcast program into a single channel (RF channel and PIDvalue) for broadcast throughout the entire network controlled by thatcontroller 1240. In a broadcast network serving a particularly largearea, there will be more than one access subnetwork controller 1240.Each access subnetwork controller 1240 will control a number of videonetwork hubs 1104 and the subtending local video access nodes 1112. Theaccess subnetwork controllers 1240 serving different areas mayarbitrarily assign one digital program into different channels in theirrespective areas. Alternatively, the access subnetwork controllers 1240may be programmed to coordinate channel assignments, so that one programchannel appears on the same channel (RF channel and PID value)throughout the network.

In the preferred implementation, a broadcast VIP will have a signalingconnection into the network. Accordingly, when a broadcast VIP 1114first establishes a presence on the video dial tone network, the Level 1Gateway will transmit a request to the PVC controller 1248 requestingthe signaling connection through the ATM backbone subnetwork 1106. Inthe preferred embodiment, this signaling connection establishes apermanent virtual circuit connection between the VIP's equipment and theLevel 1 Gateway 1108, for example, to allow the VIP to input informationregarding upcoming pay-per-view events.

In the preferred embodiment, the Level 1 Gateway 1108 will notaccumulate usage statistics relating to broadcast services. The networkoperator will bill on a flat fee basis for broadcast services. Thenetwork operator may bill the broadcast VIPs, in which case, those VIPspass on the charges to their subscribers. Alternatively, the networkoperations company and the VIP may agree that the network operatorshould develop a combined bill for network charges and VIP charges. Inthis later case, the network operations company would send out thecombined bills, collect payments, and divide the revenue between thenetwork operating company and the VIP.

A description will now be given for activation of a new customer. When aparty requests activation of a new customer (typically requested by aVIP selling video services to new subscribers or a contractor sellingDET's to consumers), that party submits a request message. If requestedby the VIP, the VIP may send the activation request to the networkcompany's operations support system (OSS) 1109 which in turn forwardsthe request to the Level 1 Gateway. Alternatively, the VIP may requestVIU activation over the direct signaling link to the Level 1 Gateway1108. For subscribers already active on the network, they may requestmodifications or upgrades in services, e.g. to add broadcast services ofanother available VIP, by a direct interaction through the network withthe OSS 1109 or with an application running within the Level 1 Gateway1108.

For simplicity of discussion and illustration in the flow diagram ofFIG. 11, it is assumed that the VIP transmits the request for activationto the OSS 1109 (step 1101). The VIU activation request includes avariety of customer related information, as well as the number of DET'sthis customer is purchasing. The request also identifies the partyrequesting the activation, in the present example, the VIP. The OSS 1109will assign and return an E.164 address for each DET 1218 to the partyrequesting activation (step S1102). The party activating the DET's willenter the respective E.164 address into each DET, using the remotecontrol, the television display and an initialization routine programmedinto the DET. The entered E.164 is thereafter considered the DET'sglobal ID.

As discussed above with respect to FIG. 8, each DET will connect into afiber node 1202 serving up to 500 homes. One access subnetworkcontroller 1240 as shown in FIG. 9 will control a number of such fibernodes 1202 through the respective LVANs 1112. For each DET 1218 of thenew customer, the OSS 1109 will transmit a message to the Level 1Gateway 1108 (step S1103). The message to the Level 1 Gateway 1108identifies the DET 1218 by its E.164 address, identifies the VIP,identifies the broadcast channels to which the VIU has subscribed, andprovides an identification of the fiber node 1202 serving the particularsubscriber.

For each new DET 1218, the Level 1 Gateway 1108 sends a series ofconnection request messages to the access subnetwork controller 1240that will service the customer. For example, the first connectionrequest might request establishment of a default signaling channelbetween the DET 121 and the Level 1 Gateway 1108. Subsequent connectionrequests would then relate to specific broadcast channels for broadcastVIP services to which the VIU has subscribed. Each activation requestprovides the access subnetwork controller 1240 with necessaryinformation for activating service, including the node ID for the newcustomer, the E.164 address of the particular DET 1218 and informationidentifying the specific type of channel requested (e.g. signaling,broadcast, etc.).

According to the preferred embodiment, each DET 1218 is assigned defaultRF channels for downstream signaling with the Level 1 Gateway 1108, theACC-4000 1242, the elements of the local video access node 1112 and theaccess subnetwork controller 1240, as well as for upstream signaling.Each QPSK mux 1178 broadcasts approximately 1.5 Mbits/s of signalinginformation downstream on a different assigned channel. The signalingdata on each QPSK channel is encapsulated in MPEG-2 packets, therefore,within the downstream signaling channel, each DET assigned to that RFsignaling channel also is assigned a PID value which effectivelycorresponds to the network address of the NIM. The main position of theDET 1218 may be assigned a separate PID value as discussed brieflyabove, but for simplicity of discussion here, it is assumed that thedata within the MPEG packets on the default signaling channel willdifferentiate between NIM messages and DET messages.

The downstream default channel through the access subnetwork preferablyprovides each DET 16 kbits/s of signaling capacity within the 1.5Mbits/s stream which is QPSK modulated by one of the QPSK modulators1178 shown in FIG. 7 into a portion of the RF spectrum not used forbroadband transmission. Also, the NIM 1216 of the DET 1218 includes aQPSK transmitter for sending signaling information upstream through thehybrid-fiber-coax loop distribution plant (FIG. 8) on an assignedchannel outside the portion of the spectrum carrying the broadbandtransmissions to one of the network controllers (NCs) 1194. The upstreamsignaling channel is preferably 400 bits/s.

The default channels and corresponding default VPI/VCI values providededicated two-way signaling communications from the DET 1218 up as faras the Level 1 Gateway 1108. For example, the DET 1218 sends a messageto the Level 1 Gateway by QPSK modulating the appropriate data in theupstream default channel. The network controller 1197 shown in FIG. 7receives the message and passes the message to the ATM router 1196 whichrepacketizes the message as one or more ATM cells identified by theupstream default VPI/VCI value for communication with the Level 1Gateway 1108. The ATM router 1196 sends the ATM cell(s) through the ATMsubnetwork 1106 to the Level 1 Gateway 1108. For messages from thatgateway intended for the particular DET, the Level 1 Gateway 1108formulates an ATM cell containing the downstream message data. This celluses the downstream default VPI/VCI value. The ATM switch routes thiscell through the APD 1174 to the QPSK modulator 1178 in the local videoaccess node 1112 serving this subscriber. The APD 1174 repacketizes thedata from the ATM cell payload as an MPEG packet data message bearingthe NIM network address PID, and the QPSK modulator 1178 transmits thatmessage through the QPSK signaling channel for downstream default signaltransport.

Although the order of the requests to the access subnetwork controller1240 could differ, assume now that the Level 1 Gateway 1108 firstrequests establishment of the default signaling channel (step S1104) andthen sequentially requests activation of a series of broadcast channels.In this example, the first connection request that the Level 1 Gateway1108 transmits to the access subnetwork controller 1240 relates to thedefault signaling channel.

In response to the default signaling channel activation request from theLevel 1 Gateway 1108, the access subnetwork controller 1240 assignsdefault channels to each new DET. The access subnetwork controller 1240also assigns upstream and downstream port identifiers and VPI/VCI valuesfor communications between the DET 1218 and the Level 1 Gateway 1108.The port identifier and the VPI for downstream signaling communicationscorrespond to an input of one of the APDs 1174 in the local video accessnode 1112 serving the VIU. The port and VPI value for the upstreamsignaling correspond to the ATM router 1196 and one of the networkcontrollers (NCs) 1194 in the local video access node 1112 serving theVIU.

The access subnetwork controller 1240 will return one or more replymessages relating to each connection request from the Level 1 Gateway1108. With regard to the default signaling channel, the accesssubnetwork controller may return an immediate reply message not shown,containing the assigned port identifiers and VPI/VCI values.Alternatively, the access subnetwork controller may return thatinformation as part of the reply message (S1106) after it completesactivation of the default channels through the NIM (S1105).

The virtual circuits through the ATM subnetwork 1106 for the defaultsignaling channels, e.g. from the Level 1 Gateway 1108 to the OC3c inputport of one of the APDs 1174, all are preprovisioned as part of thenetwork set-up. The signaling channels are allocated to each DET 1218 aspart of the DET activation routine. Hence it is sufficient to assignVPI/VCI values and ports, from inventory, to the default channels toeach DET. The Level 1 Gateway 1108 does not need to request channel setup through the ATM backbone subnetwork, as for other services such asthe IMTV session set-up discussed below.

The NIM 1216 may be considered as part of the access subnetwork. Whenthe access subnetwork controller 1240 assigns the bandwidth for thedefault signaling channels, the controller 1240 executes a procedure toactivate the default channels all the way through the access subnetworkto the NIM 1216 (step S1105). Specifically, the access subnetworkcontroller 1240 gives the E.164 address and the QPSK values for the RFdefault channels to the ACC-4000 1242. The ACC-4000 1242 in turn assignsa NIM network address to the new DET 1218. The NIM network address isalso correlated with the assigned upstream default channel bandwidth. Inthe presently preferred embodiment, the NIM network address correspondsto a PID value for MPEG packets carried on the assigned downstream QPSKmodulated signaling channel, as noted above.

The ACC-4000 1242 formulates a packet containing the E.164 and the PIDvalue. The ATM router 1244 encapsulates that packet in one or more ATMcells having the downstream default VPI/VCI value and transmits thosecells through the ATM backbone subnetwork. In a manner similar tobroadcast digital video information, the VPI value identifies an inputport of an APD, in this case one of the APDs 1174 in the local videoaccess node 1112 serving the subscriber. The ATM backbone subnetwork1106 outputs the cells on an OC3c input port of the APD 1174 assigned toprocess signaling communications for the subscriber. The APD 1134converts the payload data from the ATM cells into one or more MPEGpackets and outputs those packets on the 1.5 Mbits/s (payload) railgoing to the associated QPSK modulator 1178 for broadcast on thedownstream default channel.

As part of the initialization routine noted above, the DET 1218 willgenerate an initialization menu for display on an associated television.As part of the resultant initialization procedure, the DET 1218 willprompt for and receive a keyed input of the assigned E.164 address. Themain portion of the DET 1218 will transfer the E.164 address to memoryin the NIM 1216. When the user or technician connects the NIM 1216 tothe hybrid-fiber-coax distribution line, the new NIM 1216 will scan forand capture the broadcast transmission containing the E.164 address andthe PID value corresponding to its assigned NIM network address. The NIM1216 will also capture other relevant information, such as the channelassignments for the upstream and downstream default signaling channels.

After the NIM 1216 is initialized with the network address etc., the NIM1216 transmits back an acknowledgement signal to the access subnetworkcontroller 1240. The access subnetwork controller 1240 in turn providesappropriate information to the various network nodes, e.g. the Level 1Gateway 1108 and the ACC-4000 1242, indicating that the default channelto the DET 1218 is now activated through the access subnetwork (stepS1107).

In the exemplary procedure illustrated in FIG. 11, the Level 1 Gatewaysequentially requests broadcast channel connections, after completion ofthe procedure for establishing the default signaling channels. Morespecifically, the Level 1 Gateway 1108 transmits a connection requestfor a first broadcast channel to which the VIU has subscribed (stepS1108). The connection request identifies the DET 1218 by its E.164address and identifies the channel by its network logical channelnumber.

The access subnetwork controller 1240 provides an instruction to theACC-4000 1242, and in response, the ACC-4000 1242 sets up acommunication with the NIM 1216 and downloads decryption key for thechannel for storage in the NIM (step S1109). More specifically, theACC-4000 1242 transmits a message to the NIM 1216 using the defaultchannel and the PID value assigned as the NIM network address for theparticular DET 1218. This message specifies at least the RF channelnumber and the decryption key needed to decode the particular RFchannel. The NIM 1216 monitoring its default channel, recognizes itsnetwork address and captures the packet of message data for furtherprocessing. In the present case, the NIM 1216 responds to the message byadding the decryption key for the channel to its memory.

The NIM 1216 transmits back a confirmation message type reply (stepS1110), and the ACC-4000 1242 so informs the access subnetworkcontroller 1240. The access subnetwork controller 1240 provides a replymessage to the Level 1 Gateway 1108 indicating activation of the channelthrough to the NIM 1216 and provides the Level 1 Gateway 1108 with theconnection block descriptor for the particular channel (step S1111).

The Level 1 Gateway 1108 transmits a `set-up` message containing theconnection block descriptor to the main portion of the DET 1218 throughthe downstream default signaling channel (step S1112), and the mainportion of the DET 1218 returns a confirmation message back through theupstream default signaling channel (step S1113). The Level 1 Gateway1108 repeats the sequence of steps for activating a channel through theNIM and providing the connection block descriptor (steps S1108-S1113)for each of the channels to which the VIU has subscribed. As a result,the NIM 1216 will receive and store a table of decryption keys for theVIUs available channels, and the main portion of the DET 1218 willreceive and store a default channel map.

The default channel map consists of connection block descriptors for thechannels the subscriber is permitted to receive. Each connection blockdescriptor includes the logical network channel number used to identifyand select the channel and the RF channel in which the channeltransmission appear on coaxial cable drop into the subscribers premises.For digital broadcast services, the connection block descriptor alsoincludes one or more PID values needed to capture and begin decodingMPEG packets containing program information for the specific service(from 27 Mbits/s streams containing four broadband programs and possiblysome in-band signaling information). Preferably, the PID valueidentifies the program map packet for the particular channel.

At some point in the procedure, e.g. after confirmation of the lastset-up request by the DET, the Level 1 Gateway 1108 provides anacknowledgement back to the OSS indicating that services have beenactivated to the particular VIU, for billing purposes (step S1114). TheLevel 1 Gateway 1108 also provides an acknowledgement back to the VIP(step S1115). Depending on the interface through which the VIP requestedactivation of the VIU, the acknowledgement may go back through the OSS1109, or the acknowledgement may go directly through the signaling linkthrough ATM backbone subnetwork from the Level 1 Gateway 1108 to theVIP's equipment 1114.

The Level 1 Gateway 1108 and the ACC-4000 1242 will update the datastored in the NIM/DET as necessary, e.g., if the subscriber changes theservices to which she subscribes, if the encryption key changes or ifconnection block descriptors change because of movement of channels toother slots on the network.

For upgrades or additions to services provided to a VIU through aparticular DET, the Level 1 Gateway 1108 receives a request for theservice modification. The request may come directly from the DET 1218,from the OSS 1109 or from the broadcast VIP 1114. If from the DET, theLevel 1 Gateway 1108 may ask for authorization from the broadcast VIP1114. The Level 1 Gateway 1108 will initiate a series of connectionrequests to the access subnetwork controller 1240 to make the newlyrequested channels available through the DET 1218, in a manner similarto steps S1108 through S1113 in FIG. 11.

When the subscriber selects a digital broadcast channel, the mainportion of the DET 1218 accesses the connection block descriptor forthat channel stored in the current version of the default channel map.The main portion of the DET 1218 supplies a `connect` message to the NIMrequesting that the NIM supply signals from the specified RF channelnumber to the main portion of the DET. In response to the RF channelnumber, the selected NIM 1216 tunes to the identified channel, and theNIM 1216 uses the decryption key from its memory to descramble the tunedRF signal. As a result, the NIM 1216 passes digital signals from the RFchannel through the interface to the main portion of the DET 1218. Inturn, the main portion of the DET 1218 uses the PID value from theconnection block descriptor to begin MPEG decoding of the selectedprogram. Thus, for broadcast services, the DET/NIM stores all necessarypermission data and can begin reception and decoding in response to aselection by the user, without any upstream signaling to any other nodeof the network.

Although not shown in FIG. 11, the Level 1 Gateway 1108 may signal thebroadcast VIPs equipment 1114 for an authorization before activatingbroadcast channels for a particular VIU. For example, if a VIU isalready active on the video dial tone network, the Level 1 Gateway 1108may offer on-line service upgrade options, including the option tosubscribe to additional VIPs' services. The user would first establishan interactive session with an appropriate software application runningon the Level 1 Gateway 1108, in a manner discussed in more detail below.The user would then interact with the software application to select anew broadcast service, e.g. view option menus and select a particularpackage of broadcast services from a selected VIP. The Level 1 Gateway1108 would execute the steps S1108 through S1113 to activate therelevant broadcast channels to the user's DET only after requesting andobtaining authorization to do so from the VIP 1114. The signaling forthis authorization procedure could go through the OSS 1109, butpreferably the signaling link through the ATM backbone subnetwork 1106carries this communication for automatic real-time authorization.

There will be a flat rate monthly video dial tone charge for each VIUconnected to the network. The network operations company may bill thischarge directly to the VIU. Another option is for the network operationscompany to bill each VIU a flat monthly charge for each VIU connected tothat VIP's broadcast services. In this later case, the VIP may choose topay the video dial tone connect charge for their subscribers and absorbthat expense as part of their own rate calculations. The network couldalso charge VIUs for the number of broadcast channels which the networkhas enabled them to receive. In response to the acknowledgement messagefrom the Level 1 Gateway 1108 to the OSS 1109 when the network activatesthe various services, the billing systems within the OSS recordappropriate code in the billing record for the VIP and the VIUs.

As discussed above, the network can bill the VIPs for the networkcharges, in which case, the VIPs bill the VIUs. Alternatively, the VIPsmay provide billing information for their broadcast services to the OSS1109, and the billing systems within the OSS combine that informationwith network billing related information to develop a combined bill tosend to the VIU. In this case the network collects the bill payments anddisburses an agreed amount to the VIPs. The preferred networkimplementation is flexible enough to allow different VIPs to select eachalternative type of billing arrangement for their respective broadcastservices.

FIG. 12 is a simplified flow diagram illustrating the exchange ofmessages between various components of the network of FIGS. 5-9 duringset-up of an upcoming pay-per-view event. As shown, the VIP 1114transmits a request for the pay-per-view (PPV) event to the Level 1Gateway 1108 (step S1201). The Level 1 Gateway 1108 can receive thisrequest directly from the VIP's equipment via the signaling link throughthe ATM backbone subnetwork 1106. The request indicates the logicalnetwork channel on which the event will appear, the start time for theevent, and either the event duration or the stop time of the event. Therequest may also specify one or more windows, for free previews and/orcancellation of purchase orders. Alternatively, the VIP may supply theinformation regarding the event to the OSS 1109, and then the OSS relaysthe relevant information in the necessary format to the Level 1 Gateway1108.

The Level 1 Gateway 1108 assigns an event ID to the requested event. TheLevel 1 Gateway 1108 provides the event ID together with the informationregarding the event to the access subnetwork controller 1240 (stepS1202), and the access subnetwork controller 1240 in turn relays therequest including the relevant information to the ACC 4000 (step S1203).The access subnetwork controller 1240 provides a confirmatory replymessage back to the Level 1 Gateway 1108 (step S1204), and the Level 1Gateway 1108 provides an acknowledgement message back to the VIP 1114.The acknowledgement message sent to the VIP 1114 includes the event IDthat the Level 1 Gateway 1108 assigned to the VIP's pay-per-view event.

At the time of the event specified in the VIP's request, the ACC-4000transmits a new encryption key to the APD 1134 processing the signalsfor the network logical channel specified in the request. Only a NIM1216 storing a corresponding decryption key can decode the eventbroadcast for display via the associated MPEG decoder in the DET 1218and the associated television. As discussed below, the network willsupply the necessary decryption key only to the NIMs for subscribers whohave purchased the particular pay-per-view event. At the end of theevent, the ACC 4000 1242 transmits a new encryption key to the APD 1134,effectively disabling reception through NIMs storing the old decryptionkey. The Level 1 Gateway of the present invention permits both advanceordering of pay-per-view events and impulse ordering at or about theactual start time of the event.

FIG. 13 is a simplified flow diagram illustrating the exchange ofmessages between various components of the network of FIGS. 5-9 duringactivation of pay-per-view event reception for a video information user(VIU) or subscriber who has purchased the event.

Subscribers will be able to order pay-per-view events in a number ofdifferent ways, and each VIP offering such services may elect to allowsubscribers to use any one or more of the available ordering techniques,depending on how each VIP chooses to set up the VIP's pay-per-viewservices. The VIU may place an order with the VIP, either by a standardtelephone call or during an interactive session through the video dialtone network. In these cases, the VIP will provide the order informationto the Level 1 Gateway (step S1301), either directly through the ATMbackbone subnetwork 1106 or through the OSS 1109.

Alternatively, the VIU may order pay-per-view events through an on-lineinteraction with the Level 1 Gateway 1108 (step S1301). The Level 1Gateway 1108 provides menus through the DET 1218 and the associatedtelevision, and the user operates the remote control of the DET totransmit selection information (VIP and pay-per-view event) back to theLevel 1 Gateway. Different VIPs 1114 will require different levels ofsecurity. For example, a first broadcast VIP may choose to pre-authorizepay-per-view purchasing by all VIUs who subscribe to that VIP'sbroadcast pay-per-view services. The Level 1 Gateway 1108 thereforewould only need to check its internal database to determine if thecurrent VIU subscribes to the pay-per-view services of the selected VIP.Alternatively, another VIP may require that the Level 1 Gateway 1108signal the VIP's equipment 1114 to identify the VIU and the orderedevent, so that the VIP can validate subscription and authorize or denythe purchase for each VIU purchasing the event. The Level 1 Gateway ofthe present invention can support a variety of other security scenarios,for example preauthorization for all of the VIP's subscriber's forevents priced below a specified threshold value and validation of theVIU purchase by the VIP for events priced above the specified thresholdvalue.

In each of the ordering techniques described above, the Level 1 Gatewayreceives a request message to activate the VIU for reception of thepay-per-view event (step S1301). The activation request identifies theVIU's DET, e.g. by its assigned E.164 address, and includes the event IDfor the pay-per-view event that this VIU has purchased.

The Level 1 Gateway 1108 transmits a connection request, for connectingthe pay-per-view event to the VIU who purchased the event, to the accesssubnetwork controller 1240 (step S1302). This connection requestidentifies the DET 1218 by its E.164 address and includes thepay-per-view event ID number. The access subnetwork controller 1240instructs the ACC-4000 1242 to enable reception of the pay-per-viewevent. The instruction to the ACC-4000 1242 includes the pay-per-viewevent ID and an identifier of the DET (either the E.164 or the NIMnetwork address assigned within the access subnetwork).

In response to the instruction, the ACC-4000 1242 sets up acommunication with the NIM 1216 and downloads a decryption key for thechannel for storage in the NIM (step S1303). More specifically, theACC-4000 1242 transmits a message to the DET 1218 using the defaultchannel and the PID value assigned as the NIM network address for theparticular DET 1218. This message specifies start time, event durationand the decryption key needed to decode the selected event. The NIM 1216monitoring its default channel, recognizes its network address andcaptures the packet of message data for further processing. In thepresent case, the NIM 1216 responds to the message by adding thedecryption key for the program to its memory and stores the durationinformation.

The NIM 1216 may transmit back a confirmation message (step S1304), andthe ACC-4000 1242 so informs the access subnetwork controller 1240. Theaccess subnetwork controller 1240 provides a reply message to the Level1 Gateway 1108 indicating activation of the reception of the orderedpay-per-view event through to the NIM 1216 (step S1305).

The reply message may provide the Level 1 Gateway 1108 with theconnection block descriptor for the particular channel, in a mannersimilar to the activation of a broadcast channel discussed above. In thepreferred embodiment, however, the connection block descriptors forpay-per-view channels are supplied to the DET 1218 as part of theactivation routine. The ACC-4000 changes the encryption key for thosechannels frequently, i.e. at least for each new event. Accordingly,actual reception of a pay-per-view event on a particular channelrequires only that the ACC-4000 download the decryption key for theparticular event, as was done in step S1303.

In response to the reply message (step S1305), the Level 1 Gateway 1108does transmit a message to the main portion of the DET 1218 through thedownstream default signaling channel (step S1306). This message, termeda `facility` message contains at least the event ID and the start time.The facility message may also include the current time and the end timeor duration of the event. If the `facility` message includes the currenttime, the DET 1218 uses that time value to reset its internal clock tothe current value of the network time clock.

If the network has not already supplied the connection block descriptor,the `facility` message would provide the connection block descriptor tothe main portion of the DET 1218. The main portion of the DET 1218stores the information from the `facility` message in memory.

The Level 1 Gateway 1108 provides a confirmation message to the VIP(step S1307) indicating activation of reception of the particular eventby the particular VIU, e.g. to allow the VIP to bill the VIU for thepurchase of the event. If the VIU ordered the event via a directinteraction with the Level 1 Gateway 1108 (step 1301), the Level 1Gateway will also transmit an acknowledgement message back through theDET 1218 to provide an acknowledgement display on the associatedtelevision (step S1308).

The Level 1 Gateway 1108 transmits a request for pay-per-view eventconnection to the access subnetwork controller 1240, for each VIU whopurchased an event (step 1302), essentially causing a repeat of stepsS1302 through S1308 for each of those VIUs. At the time of the event, auser activates the DET 1218 to select viewing of the pay-per-view event.The main portion of the DET 1218 accesses the stored connection blockdescriptor for the channel carrying the event. The main portion of theDET 1218 supplies a `connect` message to the NIM requesting that the NIMsupply signals from the specified RF channel number to the main portionof the DET. In response to the RF channel number, the selected NIM 1216tunes to the identified channel, and the NIM 1216 uses the encryptionkey from its memory to descramble the tuned RF signal. As a result, theNIM 1216 passes digital signals from the RF channel through theinterface to the main portion of the DET 1218. In turn, the main portionof the DET 1218 uses the PID value from the connection block descriptorto begin MPEG decoding of the selected program and provide signals tothe associated television set so as to provide an audio/visual displayof the ordered pay-per-view event.

The `facility` message from the Level 1 Gateway 1108 to the DET 1218(step S1306) could initiate additional control functions. As noted, the`facility` message specifies the start time of the event. In one exampleof an additional control function, a software application downloaded bythe selected VIP may provide additional automatic operations forpay-per-view event viewing. Specifically, the software may respond tothe start time either to display information on the televisionindicating that the purchased event is about to begin and recommendingthat the viewer tune to the correct channel to view the purchased event.Alternatively, the software may automatically turn the DET 1218 on andselect the appropriate channel for reception and decoding at thebeginning of the event.

Although not illustrated in the process flow of FIGS. 12 and 13 forsimplicity, the pay-per-view event information supplied by the vendorwill specify at least a preview window and may specify a cancellationtime period. The ACC-4000 may instruct the relevant APD 1134 to modifythe encryption key at different times, e.g. use a first key during thepreview and a second key for the remainder of the event, and thenprovide the appropriate decryption keys for use at the correct times tothe various NIMs 1216. Alteratively, the preview may be transmitted`in-the-clear` without encryption. In this later case, the ACC-4000 onlysupplies the correct encryption and decryption keys, to the APD 1174 andthe NIMs 1216 respectively, together with instructions to begin use therespective keys at the end of the preview window.

At the end of a pay-per-view event, the ACC-4000 supplies a newencryption key to the APD 1134. In response, the APD 1134 changes toencryption of the program channel, and the old decryption key stored inthe NIMs for the previous event is no longer valid. The NIM/DETs nothaving the corresponding new decryption key can not receive and decodeany new information transmitted on the pay-per-view channel.

In the preferred embodiment, the Level 1 Gateway 1108 maintains a listof the VIUs successfully activated to receive each purchasedpay-per-view event. The Level 1 Gateway 1108 forwards this list to anappropriate billing system within the OSS 1109. If the VIP has electedto bill the VIUs for pay-per-view purchases, the purchase statistics gofrom the Level 1 Gateway to the CABS system to provide an itemized billto the VIP who in turn adds the correct amounts to the VIUs' bills.Alternatively, the purchase statistics go from the Level 1 Gateway tothe CRIS system so that the network operations company can bill the VIUsdirectly.

IMTV sessions through the network of FIGS. 5-9 will be discussed belowwith regard to the simplified message flow diagrams of FIG. 14A and 14B.

Some limited applications on the Level 1 Gateway 1108 may utilize thedefault channels. However, for most purposes, the default channels carryonly certain limited initial signaling, particularly in the downstreamdirection. For most applications running on the Level 1 Gateway 1108,the exchange of signals between the Level 1 Gateway 1108 and the DET1218 requires more bandwidth, at least in the downstream channel, thanis available through the default channel. The Level 1 Gateway 1108therefore controls the network to set up an interactive session betweenitself and the DET 1218 (See FIG. 14A). If a result of that session is aselection of an IMTV VIP 1260, the Level 1 Gateway 1108 then interactswith the relevant network control elements to establish a newcommunication session between the VIP's equipment and the DET 1218 (seeFIG. 14B).

In the preferred embodiment, an interactive session begins when the useractivates a button on the remote control specifying the Level 1 Gateway1108. In response, the DET 1218 transmits an initial services requestmessage through the upstream default channel through the accesssubnetwork and the ATM subnetwork to the Level 1 Gateway 1108 (step 1401in FIG. 14A). Based on the VPI/VCI value and/or identificationinformation in the message, the Level 1 Gateway identifies the DET 1218.

The Level 1 Gateway 1108 transmits a connection request to the accesssubnetwork controller 1240 through the dedicated virtual circuit throughthe ATM backbone subnetwork 1106. The request at least identifies theDET 1218 and specifies the desired downstream bandwidth. If thesignaling application for the Level 1 Gateway predicts a need for moreupstream bandwidth than provided by the upstream default channel, thisrequest or a separate request from the Level 1 Gateway will requestadditional upstream capacity. For convenience of discussion here, it isassumed that the Level 1 Gateway only requests a downstream channel andwill rely on the upstream default channel for upstream signalingtransport.

In response to the connection establishment request, the accesssubnetwork controller 1240 first identifies an APD 1174 having availablebandwidth capable of supporting the requested session and allocates aVPI/VCI value preassigned to that APD. The Level 1 Gateway 1108 will usea standard data transmission format, not necessarily MPEG. For non-MPEGtransmissions, the APD 1174 will extract data from ATM cell payloads andencapsulate the data in MPEG-2 packets. Preferably the APD 1174 ispreprogrammed to process cells having the allocated VPI/VCI value in aparticular manner, i.e. to provide the correct PID values in theresultant MPEG packets and to output the packets on an identified one ofthe five output rails to result in transmission over a known RF channel.If not preprogrammed, the access controller 1240 instructs the assignedAPD 1174 to provide the correct PID value in the MPEG packets and tooutput the packets on the identified output rail for result intransmission over a known RF channel. The access subnetwork controller1240 therefore effectively determines the connection block descriptorthat will apply for this session between the Level 1 Gateway 1108 andthe DET 1218.

The access subnetwork controller 1240 also identifies the NIM or the DETto the ACC-4000 1242 and indicates the relevant network logical channelnumber. If the channel is encrypted, the ACC-4000 1242 sets up acommunication with the NIM 1216 and downloads a decryption key for thechannel for storage in the NIM (step S1403). More specifically, theACC-4000 1242 transmits a message containing the decryption key to theNIM 1216 using the default channel and the PID value assigned as the NIMnetwork address for the particular DET 1218. The NIM 1216 monitoring itsdefault channel, recognizes its network address and captures the packetof message data for further processing. In the present case, the NIM1216 responds to the message by adding the decryption key for theprogram to its memory.

The NIM 1216 may transmit back a confirmatory reply message (stepS1404), and the ACC-4000 1242 so informs the access subnetworkcontroller 1240. The access subnetwork controller 1240 provides a replymessage to the Level 1 Gateway 1108 indicating activation of thedownstream channel through to the NIM 1216 (step S1405). The replymessage will include the connection block descriptor (logical channelnumber, RF channel, and PID value) for the assigned channel and the portID and VPI/VCI value assigned for this session.

Internally, the Level 1 Gateway 1108 assigns one of its own ATM outputports and a VPI/VCI value for this session with the DET 1218. The Level1 Gateway 1108 transmits a connection request to the PVC controller 1248of the ATM subnetwork 1106 (step 1406). This connection request messageincludes an originating port ID, an originating VPI/VCI value, aterminating port ID, and a terminating VPI/VCI value. The originatingport ID and VPI/VCI value are those of the Level 1 Gateway 1108, and theterminating port ID and VPI/VCI value are those of the accesssubnetwork. The connection request to the PVC controller 1248 alsospecifies bandwidth.

The PVC controller 1248 provides appropriate instructions to the ATM hubswitch 1252 and/or to an ATM access switch (not shown) to establish anactive ATM virtual circuit between the output port of the Level 1Gateway 1108 and the assigned input port of the APD 1174 and to performthe necessary translation(s) between the originating VPI/VCI and theterminating VPI/VCI. The PVC controller 1248 then provides aconfirmatory reply back to the Level 1 Gateway 1108 (step 1407).

The Level 1 Gateway 1108 transmits a `set-up` message containing theconnection block descriptor to the main portion of the DET 1218 throughthe downstream default signaling channel (step S1408). The main portionof the DET 1218 stores the connection block descriptor and returns aconfirmation message back through the upstream default signaling channel(step S1409). At this point, the Level 1 Gateway 1108 can begintransmitting downstream information through the assigned virtual circuitthrough the ATM backbone subnetwork 1106 and the assigned logicalchannel through the access subnetwork. The main portion of the DET 1218supplies a `connect` message (not shown) to the NIM 1216 requesting thatthe NIM supply signals from the RF channel number specified in theconnection block descriptor to the main portion of the DET. In responseto the RF channel number, the selected NIM 1216 tunes to the identifiedchannel, and the NIM 1216 uses the decryption key from its memory todescramble the tuned RF signal. As a result, the NIM 1216 passes digitalsignals from the RF channel through the interface to the main portion ofthe DET 1218. In turn, the main portion of the DET 1218 uses the PIDvalue from the connection block descriptor to begin decoding andprocessing of MPEG packetized signals from the Level 1 Gateway 1108.

A two-way interactive session ensues between the VIU operating the DET1218 and the Level 1 Gateway 1108 (step 1410). Although the Level 1Gateway may request and obtain additional upstream signaling bandwidth,the example given relies only on the upstream default channel forsignaling from the DET 1218 up to the Level 1 Gateway 1108. The Level 1Gateway 1108 transmits information back to the DET 1218 for processingand/or presentation to the VIU via the newly established link downstreamto the DET.

Although encapsulated in MPEG packets, either by the Level 1 Gatewayitself or preferably by the APD 1174, the data can be video, audio oruser data. The user data typically is text, signaling and controlinformation for processing by the microprocessor in the main portion ofthe DET 1218. The information from the Level 1 Gateway may comprisestill frame video information, limited and/or full motion video, as wellas accompanying audio.

The interactive session between the VIU and the Level 1 Gateway 1108 canrelate to a variety of applications available through that Gateway.Examples of such applications include on-line pay-per-view eventordering, parental control functionalities, help, change PIN numbers,customize menus, select menu languages, check billing/accountinformation, service changes/upgrades, etc. Many of these applicationsrun entirely within the Level 1 Gateway 1108 and do not result inestablishment of any further connection of the DET 1218 to otherelements of the network.

Other applications running on the Level 1 Gateway 1108 result in a needto establish a new connection between the DET 1218 and some otherservice element on the network. The connection may go to an element ofOSS 1109, e.g. to allow the VIU to review and/or modify her services.This type of situation also results when a user selects an IMTV servicetype VIP. In this later case, the preferred embodiment of the networkwill establish a broadband downstream connection between the VIP 1262and the DET 1218 and at least an upstream signaling connection betweenthe DET 1218 and the VIP 1262. Typically, the VIP has a level 2 gateway1262 and a broadband multi-media server 1264. The broadband server 1264transmits broadband information together with downstream signalingmessages from the level 2 gateway 1262 through the downstream channel.The level 2 gateway 1262 receives signaling messages from the mainportion of the DET 1218 through the somewhat narrower upstream channel.

In the present example, now assume that the interactive session with theLevel 1 Gateway 1108 (S1410) results in the VIU selecting a specific oneof the IMTV VIPs connected to the enhanced video dial tone network (stepS1411 in FIG. 14B).

In response, to the selection message from the DET (S1411), the Level 1Gateway 1108 communicates over the locked up or dedicated "permanent"virtual circuit through the ATM backbone subnetwork 1106 with the level2 gateway 1262 of the selected VIP 1260. Specifically, the Level 1Gateway 1108 contacts the level 2 gateway and indicates, through astandard message, that it has a customer calling (step S1412). The Level1 Gateway 1108 identifies the customer to the level 2 gateway, e.g. bythe E.164 address of the DET 1218. The Level 1 Gateway 1108 may alsoprovide CPE identification information and CPE-type information for theDET 1218, in a manner similar to the procedure discussed above withregard to FIGS. 1 and 2. The VIP's level 2 gateway 1262 may accept orreject the call after receiving the initial request indicating acustomer is available, in essentially the same manner as describedearlier with regard to steps S8, S8₂ and S8₃ in FIG. 2.

If the VIP accepts the call, the level 2 gateway 1262 identifies aserver output port and VPI/VCI value available for this session. Thelevel 2 gateway 1262 sends an acceptance message back to the Level 1Gateway 1108 through the dedicated virtual circuit through the ATMbackbone subnetwork 1106 (step S1413). This message includes the serverport ID, the VPI/VCI value and the downstream bandwidth. The level 2gateway 1262 may also identify a signaling port on the level 2 gateway,a second VPI/VCI value and a bandwidth for the necessary upstreamsignaling connection and include this information in the acceptancemessage.

The Level 1 Gateway 1108 will send requests to the respective subnetworkcontrollers to establish the broadband downstream link and thenarrowband upstream signaling link. In a preferred embodiment, the Level1 Gateway would transmit a single request to each subnetwork controller.The ATM backbone subnetwork inherently provides two-way connections ofspecified bandwidths in each direction. The access subnetwork, however,may be viewed as only providing individual one-way connections. As aresult, in an initial implementation, set-up of the downstream andupstream channels through the access subnetwork will require twoseparate requests and two separate procedures for establishing thedesired channels.

FIG. 14B illustrates a multi-connection request procedure forestablishing the broadband downstream channel and the upstream signalingchannel through the access subnetwork. In the illustrated example, theLevel 1 Gateway 1108 first requests the downstream channel and thenrequests the upstream channel. Other sequences are possible to establishthe same upstream and downstream channels.

At step S1414, the Level 1 Gateway 1108 transmits a connection requestfor the downstream channel to the access subnetwork controller 1240through the dedicated virtual circuit through the ATM backbonesubnetwork 1106. The request at least identifies the DET 1218 andspecifies the desired downstream bandwidth. In response to theconnection establishment request, the access subnetwork controller 1240first identifies an APD 1174 having available bandwidth capable ofsupporting the newly requested session. The APD 1174 has a VPI value anda range of VCI values assigned thereto. The access subnetwork controller1240 allocates a VCI value to this session and thereby defines anassigned VPI/VCI value for the downstream part of this session.

In the present example, assume that the IMTV VIP's equipment 1260transmits all downstream data in MPEG packets, both for programinformation and in-band signaling messages (`user data`). Preferably theAPD 1174 is preprogrammed to process cells having the assigned VPI/VCIvalue in a particular manner, i.e. to provide the correct PID values inthe reconstructed MPEG packets and to output the packets on anidentified one of the five output rails to result in transmission over aknown RF channel. If not preprogrammed, the access controller 1240instructs the assigned APD 1174 to provide the correct PID value in theMPEG packets and to output the packets on the identified output rail forresult in transmission over a known RF channel. The access subnetworkcontroller 1240 therefore effectively determines the connection blockdescriptor (logical channel number, RF channel and PID value) that willapply for the downstream portion of the session between the server 1264and the DET 1218.

The access subnetwork controller 1240 also identifies the NIM or the DETto the ACC-4000 1242 and indicates the relevant network logical channelnumber. If the assigned channel is encrypted, the ACC-4000 1242 sets upa communication with the NIM 1216 and downloads a decryption key for thechannel for storage in the NIM (step S1415). More specifically, theACC-4000 1242 transmits a message containing the decryption key to theNIM 1216 using the default channel and the PID value assigned as the NIMnetwork address for the particular DET 1218. The NIM 1216 monitoring itsdefault channel, recognizes its network address and captures the packetof message data for further processing. In the present case, the NIM1216 responds to the message by adding the decryption key for theprogram to its memory.

The NIM 1216 may transmit back a confirmation message (step S1416), andthe ACC-4000 1242 so informs the access subnetwork controller 1240. Theaccess subnetwork controller 1240 provides a reply message to the Level1 Gateway 1108 indicating activation of the downstream channel throughto the NIM 1216 (step S1417). The reply message will include theconnection block descriptor (logical channel number, RF channel, and PIDvalue) for the assigned channel, as well as the port ID and VPI/VCIvalue assigned for this session.

The Level 1 Gateway 1108 next sends a connection request to the accesssubnetwork controller 1240 for an upstream signaling channel (stepS1418). Based on available resources identified within its internaldatabases, the access subnetwork controller assigns RF bandwidth and anidentifier for the upstream channel between the NIM and the demodulator1192 and associated network controller (NC) 1194. The access subnetworkcontroller also identifies a port identifier and VPI/VCI value for theupstream communication.

The port and VPI value for the upstream signaling correspond to the ATMrouter 1196 and one of the network controllers (NCs) 1194 in the localvideo access node 1112 serving the VIU. The access subnetwork controller1240 instructs the assigned network controller 1192 to convert upstreammessages carrying the assigned identifier (temporarily corresponding tothe DET 1218) to an Ethernet format for transport through the localvideo access node 1112 to the ATM router 1196. In accord with thisinstruction, the network controller will apply an Ethernet address whichthe ATM router 1196 will map into the assigned VPI/VCI value when itencapsulates the message into ATM cell(s).

The access subnetwork controller 1240 transmits a reply message to Level1 Gateway 1108 (step 1419). The reply message contains the assigned portID and VPI/VCI value for the upstream signaling channel.

The Level 1 Gateway 1108 next transmits a connection request to the PVCcontroller 1248 of the ATM subnetwork 1106 (step S1420). This connectionrequest includes an originating port ID, an originating VPI/VCI value, aterminating port ID, a terminating VPI/VCI value and bandwidth, for boththe upstream connection and the downstream connection. The originatingIDs and VPI/VCI values are those of the server 1264 and associated level2 gateway 1262, as previously assigned by the level 2 gateway. Theterminating IDs and VPI/VCI values are those of the access subnetwork,assigned by the access subnetwork controller 1240.

The PVC controller 1248 provides appropriate instructions to the ATM hubswitch 1252 and/or to an ATM access switch (not shown) to establish anactive two-way ATM virtual circuit between the specified VIP ports andthe assigned ports of the APD 1174 and the ATM router 1196. The PVCcontroller 1248 also instructs the switch(es) to perform the necessarytranslation(s) between the originating VPI/VCIs and the terminatingVPI/VCIs for transmissions in both directions through the ATM backbonesubnetwork 1106. The PVC controller 1248 then provides a confirmatoryreply back to the Level 1 Gateway 1108 (step S1421).

The Level 1 Gateway 1108 transmits a `set-up` message to the mainportion of the DET through the still existing downstream interactivelink with the DET 1218 (step S1422). This message contains theconnection block descriptor for the downstream channel and the RFchannel assignment and packet identifier assigned for the upstreamchannel. The main portion of the DET 1218 stores the connection blockdescriptor in its memory and supplies the upstream channel informationto the control processor of the NIM 1216 for use in transmittingupstream signaling messages. The DET 1218 returns a confirmation messageback through the upstream signaling channel to the Level 1 Gateway 1108(step S1423). In the present example, this message goes through theupstream default channel.

The `set-up` message and corresponding reply message also indicate anend to the current session between the Level 1 Gateway 1108 and the DET1218. The Level 1 Gateway transmits a message to the level 2 gateway1262 indicating establishment of the broadband and signaling links (stepS1424), and the Level 1 Gateway 1108 initiates a billing record for thecall. The Level 1 Gateway also transmits tear down instructions to boththe PVC controller 1248 and the access subnetwork controller 1240 totake down the upstream and downstream session links between the Level 1Gateway 1108 and the DET 1218 (step S1425).

At this point, the level 2 gateway 1262 instructs the server 1264 tobegin transmitting downstream information through the assigned virtualcircuit through the ATM backbone subnetwork 1106 and the assignedlogical network channel through the access subnetwork. The main portionof the DET 1218 supplies a `connect` message (not shown) to the NIM 1216requesting that the NIM supply signals from the RF channel numberspecified in the connection block descriptor to the main portion of theDET. In response to the RF channel number, the selected NIM 1216 tunesto the identified channel, and the NIM 1216 uses the decryption key fromits memory to descramble the tuned RF signal. As a result, the NIM 1216passes digital signals from the RF channel through the interface to themain portion of the DET 1218. In turn, the main portion of the DET 1218uses the PID value from the connection block descriptor to begindecoding and processing of MPEG packetized signals from the Level 1Gateway 1108.

For each upstream signaling message, e.g. responsive to a user input,the processor in the main portion of the DET 1218 supplies a message tothe processor of the NIM 1216. Under the later processor's control, theNIM packetizes the message using the assigned identifier and transmitsthe packet(s) upstream over the assigned RF channel, using QPSKmodulation. The demodulator 1192 demodulates the transmitted message andsupplies the packet(s) to the network controller 1194. The networkcontroller 1194 in turn routes the message over Ethernet 1200 to the ATMrouter 1196. The ATM router 1196 encapsulates the message into ATMcell(s), applies the upstream terminating VPI/VCI value assigned by theaccess subnetwork controller 1240 and outputs those cells to the ATMsubnetwork 1106. The ATM subnetwork 1106 routes the cells to the port ofthe level 2 gateway 1262 and maps the upstream terminating VPI/VCI valueinto the upstream originating VPI/VCI value originally assigned by thelevel 2 gateway.

Using these established downstream and upstream paths, a two-wayinteractive session ensues between the VIU operating the DET 1218 andthe IMTV VIP system 1260 (step S1426).

The Level 1 Gateway 1108 times periods for confirmations or replymessages from the subnetwork controllers 1240 and 1248 and the DET 1218in a manner substantially similar to that of the embodiment of FIGS. 1and 2 to identify processing failures. Although not discussed in detailwith regard to this embodiment, the Level 1 Gateway 1108 will providedisplays to the VIU regarding various network conditions relating toIMTV call processing which are similar to the displays shown in FIGS. 2Ato 2M.

When a broadband session ends, e.g. as indicated by an exchange ofappropriate messages between the DET 1218 and the level 2 gateway 1262,the level 2 gateway instructs the Level 1 Gateway 1108 to tear down thebroadband session connections. The instruction includes the DETidentifier (typically the E.164 address) and the VIP's portidentification numbers for the VIP ports used for the broadband andsignaling communications. In response, the Level 1 Gateway 1108 stopsthe billing timing for that broadband session and transmits aninstructions to the PVC controller 1248 and the access subnetworkcontroller 1240 to tear down the broadband and signaling connectionsthrough the respective subnetworks.

The Level 1 Gateway 1108 creates a usage record for each IMTV sessionwhich will at least identify the VIU, the VIP, the start time and eitherthe duration or the end time of the session. The Level 1 Gateway 1108periodically uploads these usage records to billing systems within theOSS 1109. The billing systems bill the VIP or the VIU in precisely thesame manner as discussed above with regard to the embodiment of FIG. 1.

The Level 1 Gateway 1108 creates a log record that contains specificinformation including the time that the Level 1 Gateway received or senteach message. The subnetwork controllers provide failure reports,indicating the session to which the failure relates, to the Level 1Gateway 1108. The Level 1 Gateway 1108 then notifies the level 2 gateway1262 and possibly the DET 1218 of the network failure and terminates thebilling record for the IMTV session.

For simplicity, the above discussion assumed that the IMTV VIP 1260determined the downstream bandwidth for the interactive session when theLevel 1 Gateway 1108 first notified the level 2 gateway 1262 of theincoming call. The present invention will also permit the VIP torenegotiate the bandwidth for either the downstream or the upstreamconnections, during an ongoing IMTV session. For example, at callset-up, the VIP might arbitrarily select a medium bandwidth requirement.If the VIU orders a high definition video requiring a higher bandwidthduring the session, the VIP's level 2 gateway 1262 would transmit arequest for higher bandwidth to the Level 1 Gateway 1108. The Level 1Gateway would instruct the subnetworks to tear down existing connectionsand establish new connections as needed, in a manner similar to theprocedure starting at step S1414 in FIG. 14B, to set-up the new higherbandwidth downstream link and/or modify the upstream signaling channel.The Level 1 Gateway 1108 would record the time and new bandwidth, aspart of the record of this session.

Commonly assigned U.S. Pat. No. 5,544,161, entitled, "ATM PacketDemultiplexer for Use in a Full Service Network Having DistributedArchitecture," provides a more detailed description of the structure andoperation of the APDs, the NIM and the DET, and the description of thoseelements from that case is incorporated herein by reference.

Although preferred embodiments of the Level 1 Gateway operation anddigital video distribution networks using that Gateway in accord withthe invention have been described in detail above, it should be clearthat the present invention is capable of numerous modifications as wouldbe apparent to one of ordinary skill in the art. For example, thedetailed discussion of the Level 1 Gateway above concentrated ondata/signaling communications between that Gateway and the DET.Consequently selection menus, etc., from the Level 1 Gateway took theform of text, graphics and/or still frame data. The Level 1 Gatewaycould transmit full motion MPEG encoded video information through thenetwork in essentially the same manner as the IMTV VIP's equipment.Also, the Level 1 Gateway need not be a stand alone device. All or partof the functionality of that Gateway may be combined with that of othernetwork components, such as the PVC controller or the access subnetworkcontroller. These and any other apparent modifications all fall withinthe purview of the appended claims.

As noted, the preferred embodiment utilizes an ATM switch basedarchitecture for the backbone subnetwork 15₁. However, a variety ofother point-to-point routing technologies could be used. For example,the ATM switches could be replaced with digital cross connect switches,similar to those used in the embodiment of FIG. 1.

While the foregoing has described what are considered to be preferredembodiments of the invention, it is understood that variousmodifications may be made therein and that the invention may beimplemented in various forms and embodiments, and that it may be appliedin numerous applications, only some of which have been described herein.It is intended by the following claims to claim all such modificationsand variations which fall within the true scope of the invention.

We claim:
 1. A communication network comprising:a plurality of digitalentertainment terminals for receiving and processing digital broadbandinformation and transmitting control signals in response to user inputs;a plurality of interactive information provider systems; a backbonesubnetwork providing point-to-point two-way communication sessions forbroadband interactive multimedia communications signals with a selectedone of the interactive information provider systems; a backbonesubnetwork controller controlling establishment of point-to-pointcommunication sessions through the backbone subnetwork; an accesssubnetwork receiving digital broadband information signals from theselected interactive information provider system from the backbonesubnetwork for transmission to one of the digital entertainment andsupplying control signals from the one digital entertainment terminal tothe backbone subnetwork for transmission to the selected interactiveinformation provider system, and receiving broadcast digital broadbandinformation signals from a plurality of broadcast information providersfor selective distribution to the digital entertainment terminals; anaccess subnetwork controller controlling the access subnetwork toprovide two-way communications between the one digital entertainmentterminal and the backbone subnetwork and to control access to thebroadcast digital broadband information signals through the digitalentertainment terminals; and a gateway interacting with the backbonesubnetwork controller, the access subnetwork controller and at least theone digital entertainment terminal to establish communication betweenthe one digital entertainment terminal and the selected interactiveinformation provider system and interacting with the access subnetworkcontroller to make certain broadcast services available to authorizeddigital entertainment terminals.
 2. A communication network as in claim1, wherein the backbone subnetwork comprises at least one asynchronoustransfer mode (ATM) switch.
 3. A communication network as in claim 2,wherein the backbone subnetwork controller comprises a permanent virtualcircuit (PVC) controller.
 4. A communication network as in claim 1,wherein the access subnetwork comprises:a broadcast provider interfacereceiving digital signals from the broadcast information providers, saidbroadcast provider interface comprising:(1) means for combiningasynchronous transfer mode (ATM) cell streams having specified VPI/VCIvalues and each containing one of the digital signals into aconsolidated broadcast signal, and (2) means for optically transmittingthe consolidated broadcast signal; a plurality of broadcast headendnodes receiving the optically transmitted consolidated broadcast signal,each broadcast headend node comprising:(i) at least one ATM converterreceiving two or more ATM cell streams having specified VPI/VCI valuesfrom the consolidated broadcast signal and recovering two or more of thedigital signals from the received ATM cell streams, (ii) at least twomodulators, each modulator modulating a recovered digital signal onto anassigned channel, (iii) a combiner combining modulated channel signalsfrom the modulators into a first combined spectrum signal, and (iv)means for optically transmitting the first combined spectrumsignal;groups of central offices, each group of central officesreceiving the first combined spectrum signal from a broadcast headendnode servicing the group, each central office comprising: (a) means forproducing at least one additional signal; (b) a combiner combining theat least one additional signal with the received first combined spectrumsignal to form a second combined spectrum signal, and (c) means fortransmitting the second combined spectrum signal; andfor each centraloffice, a local distribution network transporting the second combinedspectrum signal from that central office to a group of the digitalentertainment terminals.
 5. A communication network as in claim 4,wherein the backbone subnetwork comprises an ATM network.
 6. Acommunication network as in claim 5, wherein the means for producing atleast one additional signal comprises:another ATM converter whichreceives an ATM cell stream having a specified VPI/VCI value from theATM network and recovers a digital broadband signal from the receivedATM cell stream; and a modulator modulating the recovered digital signalonto an assigned channel.
 7. A communication network comprising:aplurality of user terminals receiving and processing broadbandinformation and transmitting control signals in response to user inputs;a plurality of information provider systems; a backbone subnetworkproviding point-to-point two-way communication sessions for interactivemultimedia communications with a selected one of the informationprovider systems; a backbone subnetwork controller controllingestablishment of point-to-point communication sessions through thebackbone subnetwork; an access subnetwork providing dynamicallyallocated two-way communications between one of the user terminals andthe backbone subnetwork, and receiving broadcast information signals anddistributing the broadcast information signals to authorized ones of theuser terminals; an access subnetwork controller controlling the accesssubnetwork to provide two-way communications between the one userterminal and the backbone subnetwork and to control terminalauthorizations for reception of the broadcast information signals; and agateway interacting with the backbone subnetwork controller, the accesssubnetwork controller and the user terminals to control at least thetwo-way communications through the communication network.
 8. Acommunication network as in claim 7, wherein:at least one informationprovider system comprises a server capable of transmitting digital,compressed broadband information through the communication network; andeach user terminal is capable of processing digital, compressedbroadband information received through the communication network toprovide presentations of broadband information to the user.
 9. Acommunication network as in claim 7, further comprising an operationsand support system supplying provisioning data to the gateway to controloperations thereof.
 10. A communication network as in claim 9,wherein:the backbone subnetwork comprises at least one asynchronoustransfer mode (ATM) switch; and the operations and support systemcommunicates with the gateway through the at least one asynchronoustransfer mode (ATM) switch.
 11. A communication network comprising:aplurality terminals receiving and processing broadband information; aplurality of information provider systems; a backbone subnetworkproviding point-to-point two-way communication sessions for interactivemultimedia communications with a selected one of the informationproviders; an access subnetwork receiving broadcast information signalsand distributing the broadcast information signals to authorized ones ofthe terminals; an access subnetwork controller controlling terminalauthorizations for reception of the broadcast information signals; and agateway interacting with the access subnetwork controller to activatereception of identified ones of the broadcast information signals atidentified ones of the terminals.
 12. A communication network as inclaim 11, wherein:at least one information provider system comprises aserver capable of transmitting digital, compressed broadband informationthrough the communication network; and each user terminal is capable ofprocessing digital, compressed broadband information received throughthe communication network to provide presentations of broadbandinformation to the user.
 13. A communication network as in claim 11, anoperations and support system supplying provisioning data to the gatewayto control operations thereof.
 14. A communication network as in claim12, wherein:the backbone subnetwork comprises at least one asynchronoustransfer mode (ATM) switch; and the operations and support systemcommunicates with the gateway through the at least one asynchronoustransfer mode (ATM) switch.